Although it appears that Ellie's trip through Space actually occurred, she claims it lasted approximately 18 hours her time. This is later confirmed from the video footage, which also lasted approximately 18 hours. But the space pod was not that large, and couldn't have possibly held enough oxygen to sustain life for 18 hours. There was no supplemental oxygen or oxygen production capability inside the pod, so the only air Ellie had to breathe was what was trapped inside the pod when the door closed. She was only on the beach for a few minutes, and even then it appeared she was still within the confines of the pod which is why she was able to breathe on their planet. So if she had only the pod air to breathe, how was there enough oxygen to last her 18 hours? [The original Gemini and Apollo capsules from the US Space Program weren't that much larger than the pod and they were capable of sustaining people (often more than one) for much longer. The pod was based on alien technology and had a sophisticated air re-circulation system.]

Ellie claimed her space trip lasted approximately 18 hours, but from what we saw it seemed more like 15 or 20 minutes at the most. She made it through the initial worm holes in several minutes, spent several more minutes on the beach with the Alien - and then as she later testified, an instant later she was beamed back to Earth as she splashed down. How does this possibly add up to 18 hours, when the trip was really only several minutes long? We were seeing the trip in her time, as it actually unfolded. [No we weren't seeing the trip in her time as it unfolded. No audience is going to sit through 18 hours of uneventful footage, so, as usual, they use time compression to give us only the highlights.]

When Angela Bassett is speaking during the Press Conference, she mentions that the Signal was discovered at 6:31 a.m. Mountain Time. New Mexico is probably in Mountain Time zone, therefore this time would be accurate in the early morning. But Ellie actually discovers the Signal while lying on her car during the evening/dusk, and rushes back to the control room, where they work through the night processing the signal and discovering the Primes. In fact, one of the guys working there mentions that they have to do something soon, as Vega would be setting, meaning it was becoming night. [She misspoke. She should have said the signal was confirmed at 6:31 after verifying it from other sources in other countries. Because Vega was setting soon, they contacted Australia to track and confirm the signal. NM is in the moutain time zone. If anything it's a character mistake.]

When Haddon is showing Ellie's life story to her on his plane, he mentions that she turned down a teaching position at Harvard in order to do research work for SETI at Aericibo. But the video clips he is playing for her at that point show her actually teaching from a podium, using a screen behind her. This implies that she was physically teaching at Harvard, although in reality she never took the teaching position in the first place. [She could be presenting a paper at a conference, or making a budget proposal. Simply standing at a podium with a screen behind her isn't nearly enough to suggest that she's taken up a specific teaching position.]

Ellie drives her jeep to confront Drumlin after learning he's pulling the plug on their research funding. She begins her typical argument, "there are 400 billion ." and he cuts her off with, "two possibilities: 1) they're so far away you'll never contact them, or 2) there's nothing out there but noble gasses and carbon compounds" . (ahem) the top 10 elements of which our local sun is comprised are: Hydrogen, Helium, Oxygen, Carbon, Nitrogen, Silicon, Magnesium, Neon, Iron and Sulfur (that's two noble gasses out of 10 ?) and isn't carbon-based life what they're looking for? so . carbon-compounds wouldn't be a bad thing to find, now would it? [Drumlin's being sarcastic. (1) This is not intended as a serious scientific statement. We all know that there are other elements out there, and so does Drumlin. (2) Ellie's using a radio telescope. (ahem) Do you really think that carbon compounds are noted for sending out radio waves? They don't, so she's not going to find any. And, just for the record, neither do noble gases. Which merely emphasises the point; Drumlin's just being sarcastic about her chances.]

Ellie tells Palmer, "There are 400 billion stars out there . just in our galaxy alone. If only one out of a million of those had planets, alright, and if just one in a million of those had life, and if just out of a million of those had intelligent life . there would be literally millions of civilizations out there." Such a brilliant MIT grad, should be more convincing using mathematical arguments: 4.00E+11 x 1/1.00E+6 x 1/1.00E+6 x 1/1.00E+6 = 4.00E-7 (that's 0.0000004 planets in our galaxy with life!) Not a very persuasive argument for vast quantities of life in the universe. [Yeah, well, with the current estimate being that there are over a hundred billion galaxies in the observable universe, many of which are deemed to be considerably larger than our own, I think you'll find that Ellie's statement is, in fact, perfectly correct.]

In the public inquiry at the end, Ellie says she was gone "approximately 18 hours". But this contradicts what she says right after the capsule lands: "What day is this? How long was I gone?" So how did she come up with 18 hours? We do find out after the inquiry is over that her headset, conveniently, recorded 18 hours of static, but this was kept secret by the investigating committee. So Ellie didn't know that; in fact, she had no way of knowing how long she was gone. [It's not remotely unreasonable that she couldn't have worked out an approximate timeframe later on, once she'd had to time to reflect on her experiences. She also knows that she's travelled through what appears to be a wormhole - under those conditions time can (and, as we find out, has) run strangely, so she has no real idea how long she might have been gone from their point of view, so her question is hardly unreasonable.]

Hadden tells Ellie that the zero gravity and low oxygen environment aboard Mir is slowing the progress of his cancer. Quite apart from this being medically absurd, he isn't breathing Mir's atmosphere - he has a nasal air line installed. [A zero gravity environment can have drastic effects on the Human body, such as decrease in body mass and less muscle strength, to name a couple. It also causes the body to lose a great deal of fluid which would normally be forced down into the abdomen and legs by gravity. (This is why Shuttle astronauts have to force-drink mass fluids just prior to re-entry, to avoid light-headedness from the pronounced lack of fluid their bodies are still experiencing while re-entering a gravity atmosphere). It's possible theoretically that zero-gravity could also have an effect on aggressive cancer, and the entire premise of this movie is theoretical. Also, the nasal line could be to make it easier for Hadden to breathe in his weakened condition, adding some oxygen, but at the same time he was still breathing in the overall atmosphere inside the Space Station as the line wouldn't completely block his nose and mouth.]

In the scene where the alien machine is activated for the 2nd time. The ships are shown to lean toward the machine (as a result of the gravity field it creates). Boats float orthogonally (horizontally) to the direction of gravity. If the machine generated a gravity field that "pulled" then the ships should be seen tilting away from the machine... in order to float orthogonal to the direction of gravity. [That would depend on the exact direction of the gravity pull. Since the centre of the machine (and hence the centre of gravity) is located several hundred metres above ground level, the force would attack at the upper structures of the ships. This would cause a tilting as it is depicted.]

After the signal from Vega has been established to contain an encrypted message, some of the world's most skillful cryptographs are set to decrypt it. After weeks without any success, Mr. Hadden finally reveals the solution to Ellie - the squares making up the message have to be put together like cubes rather than in a 2D grid. This seems fair enough from a cinematic point of view, because it gets Ellie back on the track. However, it is hardly logical. In reality, one of the first things a skillful cryptograph would do when getting those squares with markings in the corners would be to try putting them together like cubes. Thus the message would have been decoded in much less than a week. [Simply because you think that is the first thing they would do doesn't mean it is a movie mistake. It's kind of like all the people in scary movies running upstairs. Character mistakes.]

When Jodie Foster comes down off the helicopter, she and Tom Skerritt are interviewed on the spot (that happens minutes before the explosion of the first engine). This interview last about 3 or 4 minutes, at most. But if you look in the background, you will see a countdown panel. At the beginning of the interview, it shows 2h01 and at the end, it shows 1h53 instead of the expected 1h57. [There was a time lapse and they didn't show the full interview. ]

Easy way to tell how long the trip was - she bangs her head and it starts bleeding on the trip - if it only lasted seconds then it would still be bleeding, but if it lasted hours then it would have healed... [She bangs her head after the trip when the device falls into the net.]

Towards the end of the film, when they review Foster's footage of her supposed space trip, they note that about 18 hours of static has been recorded, but she was only off the cameras for a split second. Foster claims to have traveled to a distant region of space and claims the trip may have lasted for hours (the camera static supports this), and that the cameras on the machine may have only missed her for a split second "Earth time". But, this contradicts Einstein's special theory of relativity, which states that time will slow down for objects traveling closer to the speed of light (which Foster was doing) relative to objects at rest (observers on earth). If Foster truly traveled for almost 18 hours, as she states, and as her camera records, then it would be impossible for the stationary observers on Earth to see her gone for only a split second. They would have to had to recorded her as being gone for far, far longer than 18 hours. [A slightly technical answer, but Sagan has used another consequence of general relativity to get around the time-dilation effects of close-to-luminal velocities. The Einstein-Rosen bridge, or 'wormhole', is link between two distant points in space which allows matter and energy to travel between them without crossing the intervening space. Now the ?wormhole? get out is not without its own problems - which it is well beyond our current capability to even comprehensively understand never mind solve. Purely in theoretical terms though it would allow both for Ellie to travel to distant areas of the galaxy at (effectively) faster-than-light speeds, and also to (effectively) travel back in time by arriving back at her start point with zero time elapsed after a journey of 18 hours. Unfortunately the ?worm hole? has been used in a number of other slightly less fastidious sci-fi settings (Star Trek Deep Space 9, Stargate SG-1) and might now be seen as being something ridiculous or impossible. Whilst the portrayal of wormholes in these programmes is often based more on fantasy than science, the underlying theory is sound, as one would expect from a scientist with Carl Sagan?s reputation. Indeed in his updates to the seminal factual series ?Cosmos?, Sagan mentions his discussions with Kip Thorne about the use of wormholes as a plot device in ?Contact?. For more information about our current understanding of wormholes see ?The Universe in a Nutshell? or ?A Brief History of Time? by Dr. Stephen Hawking.]

During Jodi Foster's "trip" she releases herself from her chair which eventually breaks and smashes in the sphere. This couldn't have happened during the tenths of a second of the sphere's fall without her being seriously injured, so that might be a good proof that the trip really happened. [Well, the U.S. Government knows the trip really happened, they covered it up, so it's unlikely they will let the public know that the chair broke off, it would make people ask questions.]