Deliberate mistake: If you pay extremely close attention to the scene of all of the Decepticons responding to the small Transformer's message regarding the location of the Allspark, notice that the shot of the police car and the fake helicopter pilot are duplicate shots used earlier in the film.
Deliberate mistake: When Agent Hoffman writes the letter to Amanda, he puts the envelope so her name is pointing down, yet when Amanda opened this drawer in Saw III her name was at the top. The director had to do this or it would have revealed Hoffman was the new apprentice all along.
Deliberate mistake: During the fire Marge runs back into the house and goes to the kitchen cabinet that has a "keepsake cabinet" nameplate and a keyhole, in order to remove the wedding video, but the nameplate and keyhole didn't exist before. (00:33:35)
Deliberate mistake: After the broken suspender clasp smacks Gerry in the face, in the close-up it lands under the dresser, within the wide strip of light reflection. In all other shots the entire area beneath the dresser is in shadow. (00:11:00)
Deliberate mistake: Main headlines in newspapers appear translated for each country for the kids to understand it, but the rest of the news appear in English, despite the movie taking place in Paris. Also, most signs -such as the poisons in the window shop- have labels written in English.
Suggested correction: By that logic, it's a mistake that the characters speak English. It's an American movie set in France, and like you said, it's a kids' movie. Everything is in English for simplicity's sake.
Deliberate mistake: Loch Ness is portrayed as a clear lake, as shown in the underwater scene. In real life, Loch Ness is so murky there is only six feet of visibility. Obviously deliberately done for the sake of the storyline.
Deliberate mistake: During the scene where Carlos and L.J. are searching the motel, L.J. sees a zombie which turns out to be a reflection in a wall-length mirror. L.J. shoots, breaking the mirror and realizing his mistake. But, if he had been standing in front of the mirror as shown, he should have seen his own reflection standing there as well. This was done as an homage to a similar encounter in the original game. (00:24:20)
Deliberate mistake: In Antarctica when Charlie and Cam kiss, their tongues become froze together but this is impossible as it would take a freezing object for this to work.
Deliberate mistake: When Randy is playing with Agent Rodriguez's gun (after first meeting him), when he accidentally fires it, you can tell the film inexplicably cuts forward a few frames into the same shot, as Randy's body suddenly shifts position and the gun is facing upwards, rather than at an angle as it was the frame before.
Deliberate mistake: At the end of the movie, where the girls chase stuntman Mike, they drive the upper dusty road. When their car is shown front outside angle, there's a lot of dust rising from the camera crew's car. But when the camera angle gets into their car and shoots strait ahead - the dust is all gone, the air is perfectly clear.
Deliberate mistake: When Evan/August first meets Arthur at the park, after playing, you see Arthur leaving his spot without taking the cable and (presumably) the amp as well.
Deliberate mistake: After Prof. Broom finally defeats the vampire countess near the end of the movie, many of her ghostly victims appear around the room. And, if you look closely, you can see that many of them look exactly like one another, revealing that the animators simply would repeat the same images over and over onscreen, to make the crowd bigger. (Confirmed in DVD commentary).
Deliberate mistake: In the facial morph, the faces don't come anywhere close. The face was morphed with no feature of either resembling the other. The only matching features were the hair and neck which were not touched by the morph. The midpoint of the shift wreaks of Photoshop-like effects (softening of the face alone). (00:41:50)
Deliberate mistake: Below deck aboard the Pearl, when Will says, "You make your choices in life ," and later, when Elizabeth and Will are on the beach, Elizabeth's eye makeup and curled up lashes are very apparent in her close-ups.
Deliberate mistake: In the scene where Mr. Bean is hitch hiking, right before the shot where the truck runs over the wooden box, there is a wide angled shot. The road is very long and it is clear that there is no truck coming. In the next shot, the truck suddenly zooms by from the right of the screen. This can also be seen on the trailer. (00:44:30)
Deliberate mistake: During the final montage, we see Erik and Joyce in bed together, and the next sequence is of Teddy talking to his baby brother. This was to show that they got back together and had another kid. The mistake is that Teddy would've been a year older by that time, and so would've looked a little bigger, although there is also the fact that the actor who played Teddy (Dakota Goyo) was between 7 and 8 for the filming. (01:47:30)
Deliberate mistake: During the bathroom scene where Jimmy is trying to get the key to unlock himself from the handcuffs after the little Asian boy had knocked over the garbage can, the toilet paper roll should have had the cardboard tube attached to it upon reaching Jimmy and should not have various pieces of garbage on it.
Deliberate mistake: When young Becca picks up the drawing that young Seth made, in the first shot, as she flips it over to look at it, you can faintly see the pen-marks through the paper, and they are not the same as in the following close-up shot, when we see the actual drawing. In the first shot, they seem to be a grouping of rectangular shapes, whereas in the second shot, it is obviously a large drawing of a penis. They had to use different pictures due to child labor laws that wouldn't permit the young actress from seeing the actual picture, and so a hand-double was used for the close-up shot. (00:17:15)
Deliberate mistake: The floating contact mine that explodes at the end of the movie would never have been put in an evidence room in a police station. Barring that error for the plot's sake, FCMs weigh 450lbs and would have required a hydraulic crane and a cart to move it, not just a couple of guys. They also did not contain clocks. (00:42:40)
Deliberate mistake: In the scene where the Wild Hogs are driving past the bikers' bar, Woody uses his throttle hand to show the bikers his middle finger, yet the bike is still able to accelerate.