When they send the warning note to Denzel Washington from the present to the past, it takes so much power that the whole "time machine" system as well as the power in the whole city breaks down. When they send Denzel back to the past it happens much faster and without any problems. When the "transfer" from Denzel to the past works that fine, a transfer from a simple paper with some words on it should be no problem at all. They also said that they tried to send a hamster to the past and that it did not survive it. Why should an adult survive this? [Rule of thumb with plot holes is that it must contradict something in the film. Something not making sense is not the same as being wrong. Denzel might have survived compared to the hamster as human beings have the ability survive and withstand more than many animals and mammals.] Corrected by Lummie

After the ferry explodes at the start of the movie and they start evacuating survivors, there is a shot of people waiting on the dockside talking to a cop. One of the people, a black man with dreadlocks in a white T shirt is smiling at the cop, while the others are shouting a him. Bizarre considering the disaster that had just occurred. [Bizarre, yes, but not a movie mistake. People cry at weddings, laugh at disasters, and attack emergency personnel who are there to protect them all the time.] Corrected by MovieGuy

After going back in time, Carlin appears at Charity Hospital. Charity Hospital has been condemned since Hurricane Katrina and would have still been flooded inside during the time frame of the movie. [Deja Vu started filming before, during and after Hurricane Katrina. There's nothing to say that the shots of Charity Hospital were not done before the hurricane struck, and since the film makers could not predict the hurricane nor the condemnation of the hospital, it is acceptable to include it in the movie.]

In the first time line Clair lost 4 of her fingers and she washes up on shore at 10:48. In the second time line Doug saves her from loosing her fingers and stops her from dieing by the bad guy burning her and dumping her body. Back to the first time line and finally to the plot hole. If she looses her fingers in the first time line and is suppose to be dead then how is she in her apartment to answer the phone when Beth calls? In the second time line Doug tells her what Beth says to prove he knows what is going to happen in the future, he knows this because he played her messages back in the first time line. How did she answer the phone if she was dead and about to wash on shore? [I suppose the easiest and simplest way to answer this is that there is a new road or branch in the timeline that was created, which is explained by the black woman in the film.]

Carlin realizes that the bomber only needed to steal Claire's vehicle because Carlin's partner shot up the windshield of and got blood in the bomber's own car. Otherwise Claire would not have become involved at all. The problem? As they are watching the events of the past, they see the bomber calling Claire about her truck BEFORE Carlin's partner confronts him and shoots his windshield. [The bomber rang Claire about her truck because he was keeping his options open. Perhaps truck owner 1 wasn't answering his calls so he rang Claire about hers, but then he got truck 1. Then when it was ruined, he had Claire's as a back-up.]

Carlin was wounded when he saved Claire from being killed and her fingers dismembered. After that Claire bound Carlin's wounds in her home and put bloody bandages into a basket. It is not possible to have dead fingerless Carla and the bandages in the same time branch. [The timelines are not crossing. The bandages show up the exact same in this time line (as the movie carefully points out through other details as well, such as the phone call), is that no matter what Denzel does to stop Claire from dieing and the ferry explosion, the events are still falling into place. This was explained earlier when we find out that although Denzel effected his partners death by sending a note back in time, his parter still died and Claire did as well because he was not able to change the timeline enough.]

During the film, when Doug Carlin is in the "present" unaltered time, he sees things that eventually happen later in the movie when he goes back in time. What doesn't make sense is that if he saw all the other things, and considering he saved the ferry, how could he see the ferry explode at all in the beginning? [That's exactly why he went back in time in the first place, to keep the ferry from exploding. One of the great questions to time travel is what happens to the present when you go back in time. during the movie it is alluded that you create a different branch of time when you go back. In this case that "present" ceased to exist when Doug went back in time. In doing so he created a new "present" time, and erased the "first present" time that is shown at the start of the movie.] Corrected by Nick Bylsma

Surely if Doug can go back 4 days and he's saved the people on the ferry then why can't he go back again to stop Larry dying? [Doug saw Larry's death which happened 4 days ago. He can't go further back in time to stop that because of the 4 day limit in the time machine.]

At the beginning of the movie, one guy in Doug's office gives him Claire's message, written on the outside (colored side) of a candy wrapper. When Doug goes back in time, the guy gets Claire's call again and he grabs the candy wrapper, beginning to write on the opposite side of the wrapper. [The wrapper (which was a gum wrapper btw) had no handwriting on the colored side. It did however have black printing that was blurred by the film quality. When Greg is dialing the number he is clearly looking at the white side.] Corrected by zephalis

Just before the bomb explodes at the beginning of the movie, the guard is looking for the car playing 'don't worry baby' on it's stereo. In the final timeline the disaster has been averted, the bomb having gone off, and the ferry docked. After this, when Carlin is in the car, the same song is playing, but the bomb was set to a timer. [That's why the movie is called Deja Vu and thats why Carlin gives the girl such a strange look. The song triggers a feeling of Deja Vu for him and it almost feels to him that he knows her. Besides, a different station could have been playing the song.] Corrected by SexyIrishLeprechaun

Using logic then this movie does not make sense. The "you can save her" on the fridge, the blood stained clothes and the cotton swabs. These were all done by Doug in the past. If Doug in the past managed to show this to future Doug as he was looking around the house for clues then surely he'd already done the deed of stopping the ferry. [This is complicated, but the way I understand it is that Doug in the past had tried to stop the ferry but failed.]

While listening to Claire on her cell phone, why can they hear the other side of the conversation? [Some phones are loud - I have a phone that every person in the same room can hear, not just the person speaking into it.]

Carlin forces the other agents to confess about the fact that they were really looking at the past in real-time and not looking at 4 day old footage. The way he does this is to shine a laser pointer into the equipment. It took amazing amounts of effort and machinery to send any item back in time. Even accepting that the infinitesimal size of the laser beam's particles would make it very easy to send the beam: WHY would it work that way pointing it at a MONITOR? It's just a viewing screen and is only 1-way. Further proof that it's just a monitor and not a 2-way portal: When they zoom through the scenery with the cameras in space (and yes, they were honest about the placement of the cameras) the screen shows that it takes a bit of time to render/display the image. [Remeber Carlin asks if the person in the past knows that they are being watched and the scientists don't know the answer for sure. It seems apparent that they do have some effect on the past just using the view portal and without using the larger machine (e.g. the girl comes out of the shower 'knowing' she is being watched). Therefore it is entirely possible that shining the laser also had some effect on the other side of the timeline too - it certainly caused a minor power fluctuation. It just happens that the machine for sending larger things through the wormhole is just bigger and takes even more energy.]