Deliberate mistake: In many of the non-CG generated snake shots, what appears to be a very venomous coral snake is in fact either a scarlet king snake or a California mountain king snake (depending on the shot). These are much safer, non-venomous alternatives for filming with the actors. Look for the ordering of the colored bands (red/black=venom lack, red/yellow=kill a fellow).
Deliberate mistake: When Carrie is hiding in the locker room to record John talking with his friends, it's clear that her camera is behind the vent, and the openings in the vent are closer together then the diameter of her camera lens, however we don't see the vent slats in the camera view or the replaying of the video footage in a later scene. Not to mention the fact that she isn't holding the camera steady. This is impossible.
Deliberate mistake: During the movie, when Mulan is just a girl, you can see that her eyelashes extend beyond her eyes. When she is pretending to be a boy, her eyelashes are short (this makes perfect sense). But when she is in the medical tent her eyelashes are long even though she had no time to put on makeup. This is deliberate though, because without it she would have still looked like a boy, and just pulling her hair down wouldn't make her look any different (since that's how she looked in the pond). So they had to change her eyelashes to make her look more girlish.
Deliberate mistake: This film contains the most stupid scene ever filmed. Linda Koslowski dips her canteen in a creek and a full grown crocodile grabs it and tries to drag her into the water - and she holds it off in a tug of war until our hero Mick arrives and kills it. Nonsense. A slightly built woman has a much chance of holding her own against a 1200kg croc as I have of flying to the moon. She'd be croc food before he even heard the splash - a croc that big could take a 1000kg buffalo without pausing for breath, never mind a small woman.
Deliberate mistake: Father Merrin says, "It is He who commands you", and we hear and see the ceiling crack above his head. In the next shot we see the ceiling above him and they are no cracks in it, but four shots later we see the exact same spot and now cracks appear even though we hear no more cracking over-dubs after the first one. (01:49:15)
Deliberate mistake: When Bullitt enters the hotel room to do a Recki, we see photos of the injured man on the wall. From this we can conclude one of two actions. 1: The ambulance crew took so long to arrive, the police had plenty of time to take a variety of photos from many angles. 2: The police did not let the medics in until they had taken their photos of a man who was in need of immediate medical attention. Wouldn't the injured man rather have his wounds seen to first than his photo taken?
Deliberate mistake: This was probably done intentionally to make them more visible, but the bullet holes left in the stairwell wall by Bart's handgun while he is chasing Danny during the movie's climax look to be about the size of golf balls. Typical handgun calibers aside, just looking at the size of the clip he's loading into the gun and seeing how many rounds it holds, those rounds would have to be much smaller than the holes the bullets made.
Deliberate mistake: After Carmen rescues Juni on the boat/sub, he accidentally re-engages the autopilot and they submerge. In the next shot as two Thumb Thumbs jump off their speedboat, the name, 'Donzi', that is written across the side of the boat, is backwards. This shot is flipped. (00:24:10)
Deliberate mistake: During the rumble scene there is a "Soc" whose clothes are completely dry and clean right before the Socs surrender. He's wearing a light blue shirt.
Deliberate mistake: During the chariot race, the chariots crash together but the arrangement of the horses make it impossible for them to actually collide. In some instances (particularly in an aerial shot as Ben Hur and Messala round the turn) it is obvious that they repositioned the shaft of the chariot to between the first and third horses instead of being in the centre between the second and third.
Deliberate mistake: While most of the German spoken in the movie is correct (even if with bad accent) there is a translation error in the scene at Yankee Stadium. The accent suggests that these bad guys were raised in the communist eastern Germany and previously served in the secret service "stasi." When the guy with the sniper rifle gets nervous and asks if he should shoot or not, the other one says,"Nein, wir brauchen den anderen", which would translate, "No, we need the other one", but the subtitles say, "We'll follow him", which they do.
Deliberate mistake: The car Rudy, the mechanic, is working on is a 1971-72 Plymouth (the one where the chassis falls down around him). Plymouth's of that era were unibodies, which means that the body and the chassis were all one piece and not separate, so there's no way a chassis could have fallen down like that from that particular car, since it didn't have a separate chassis.
Deliberate mistake: In the scene where Forrest is describing his heritage, the clip of KKK on horses is taken from The Birth of a Nation. In this clip, you can see tire tracks on the dirt road well before automobiles were supposed to be in existence. Robert Zemeckis decided to leave this mistake in to perfectly match the clip to the original movie.
Deliberate mistake: In the scene where the Punks follow the Warriors into the bathroom, Rembrandt sprays the head punk with his red spray paint. However, the spray coming out of the can is clear, not red.
Deliberate mistake: In a lot of the shots in the cockpit, when Teri is attempting to begin taking control of the aircraft, notice the Horizontal Situation Indicator on the First Officer's side. The compass rose is moving around erratically - which would suggest that the 747 is also changing heading extremely erratically and robotically - which isn't possible.