Deliberate mistake: In the opening title sequence, just after the title of the movie is shown, Puss cuts a P with his sabre into a curtain or flag. In the middle of the P, there is cloth remaining, but since he cuts edges all around this to make the Capital P, this cloth should fall away as it is no longer attached to anything, yet it floats in mid air.
Deliberate mistake: When Adam kills himself and Hector at the end, the explosion sends a lot of water and parts of Hector into the air. But there is no sign of Adam's blood, body parts or clothing, despite the fact that the bomb was strapped to him. (01:16:10)
Deliberate mistake: Some of the text in this movie is in English, but some is in Japanese. Most noticeable when Tai writes the letter to Sora.
Deliberate mistake: When the rocket (a replica of an Atlas booster) launches, it makes it all the way to orbit in one piece. In reality the Atlas was a two-stage rocket, and the first stage would've been jettisoned long before reaching orbital velocity. (Undoubtedly the filmmakers decided to fudge this, to avoid dealing with the issue that the rocket didn't launch over the ocean, and the first stage would've fallen onto some innocent bystander's property.).
Deliberate mistake: While the rock n' roll musical is ending, it shows the hot air balloons in the background and it shows Dave up close. He talks to himself confused, trying to figure out if he really saw his boys there or not. But if not being able to notice, wouldn't he at least hear them singing in the background as well as we can? Also, before, while Alvin and Britany were dancing together, he was trying to get to them before the two bad guys could, as if he knew for sure they were his boys and that those guys were out to get them.
Deliberate mistake: During the space battle, one of Drax's men gets his back pack blasted. (1:46:37) His entire pack explodes so that his jet pack and life support are destroyed. But as a result of that blast, all the parts from his suit FALL DOWN! Even though there's no gravity.
Deliberate mistake: When Scrat's coconut falls from the tree, it has already had its husk removed. The directors confirm this on the DVD commentary. They may have been worried that a lot of their audience would not recognise a coconut with its husk on. (01:11:45)
Deliberate mistake: On the map showing the location of all the 'Camel Hump' refuelling blimps, none of them are anywhere near the countries EDI visits in the film - the nearest one is more than a thousand miles away over the Pacific.
Deliberate mistake: None of the helicopter's in the movie have the Army markings seen on Vietnam era Hueys. The most you'll see is some crooked, faint and inaccurate stencils in the wrong spots. (00:37:50 - 00:51:25)
Deliberate mistake: The huge bruise on Tommy's face, from the board hitting him, disappears in less than a day.
Deliberate mistake: Foils, rapiers and other fencing weapons did not appear before around the 16th/17th century, yet the main characters (in an approximate 8th to 10th century setting) use them extensively. I know that back in the days when the movie was made, the swashbuckling genre was quite popular, but it still is a reality error.
Deliberate mistake: In the scene where the characters are initially signing up for the contest, Gene Hackman's henchmen cock their weapons as they enter, then after Sharon Stone shoots the rope apart the henchmen cock their rifles again. The problem is that with a second cocking the rifles would be ejecting any chambered brass. It seems like a deliberate mistake because they cock their rifles an inordinate number of times throughout the movie; I would guess the director wanted the effect of hearing the weapons being cocked multiple times at the expense of continuity with the rifles.
Deliberate mistake: When Bastian comes running up the stairs by the harbour, you can see a black couple on the right. The woman is wearing a grey coat with a black vest and a white shirt. The man is wearing a black coat, black shoes and white socks. When it cuts to Bastian running across the street, you can see the exact same couple wearing the exact same clothing crossing the street, but this time they are not walking together. The extras were used twice. (00:11:10)
Deliberate mistake: When the tribe does the ceremonial dance to bring the crow back to life, you can see the same shot of the bird leaping up twice.
Deliberate mistake: When the raptor breaks into the control room and is hopping around the computer workstations, we see sharp, distinct genetic coding projected from a computer screen and across the raptor's face (starting 1:55:50). Aside from the fact that computer displays have never projected focused images onto nearby surfaces, the projected text shown in this scene oddly reads from left-to-right, when it should actually be a flipped mirror-image (right-to-left). Spielberg probably realised this factual incongruity while filming but chose to use the left-to-right text for the sake of audience recognition, given that the multiple lines of "GATC" genetic code were already confusing enough. (01:55:50)
Deliberate mistake: One of Eva Marie Saint's lines in the dining car seduction scene was re-dubbed. She originally said, "I never make love on an empty stomach," but it was changed in post-production to "I never discuss love on an empty stomach." It is said that the censors felt the original version was too risqué.
Deliberate mistake: When 11 is dropped into the water and eaten by the piranhas, although the ravenous fish probably ate most of her and what was on her, there should at least be pieces of clothing that would rise to the surface in the flurry of activity. Not to mention that even though the water is a murky green all the blood from her body should have created a temporary, but very noticeable darkening of the water.
Deliberate mistake: It's not possible for Chance to have been able to launch the cougar off the cliff with just his own weight.
Deliberate mistake: During Lansbury and Dr. Brown's dance scene under the water, the drawings behind them (with couples of fishes sitting on their seats) are a still drawing, no animation at all.
Deliberate mistake: When her father jumps on the brakes, they lock up, even though the car is supposed to have ABS, which is supposed to prevent this from happening.