Deliberate mistake: Throughout the movie, you can see the size of true-size Rosemary, particularly her waist and legs. Notice the size of undies she was going to purchase when she and Hal first meet. Notice the size of her bathing suit bottom. However, in the scene where she throws her purple nightie undies at Hal and he catches them: the panties are WAY TOO BIG. Especially the leg holes, which could go around her true-size waist.
Deliberate mistake: As David runs from the MP's in the restaurant, he jumps off the balcony onto the bar below. It is very obvious that it's the stunt double for Michael Pare doing the jump. (00:45:35)
Deliberate mistake: When women are being shown naked by the x-ray machine, they look wrong. If the machine just sees through clothes, their breasts wouldn't look normal, but squashed together and supported by a bra.
Deliberate mistake: The same group of people wearing the same clothes, including a dancer and bartender, are shown sitting around a bar on two different disco nights. On the first disco night we see them when Tony leaves the bar to go outside after being informed by Joey, what Double J is doing in the car. We see these people again at the start of the second disco night, both nights when we see them, the song "If I Can't Have You" is being played. (00:21:20 - 00:56:30)
Deliberate mistake: When the girls are done snorting the "coke" and Rick takes the tray away, none of the girls have snorted any of it because the same amount is still there except instead of lines it is now all muddled together. Also if you watch closely when they are snorting the coke, the rolled up bill only gets close to their nostril and not partially inside it. (00:09:45)
Deliberate mistake: Before going on stage in the infamous purple coat for the first time in the movie, the Kid is in his dressing room. The silver jewelry/decoration on his coat is on the left shoulder. In all subsequent shots, the silver jewelry/decoration is on his right shoulder.
Deliberate mistake: In the scene where we see Bella in her room looking out the window, the months are passing, but she is always wearing the same clothes. (00:28:30)
Deliberate mistake: After Sharpay falls into the pool, when Gabriella dives in it is an obvious stunt double for the actress. (00:16:40)
Deliberate mistake: When the father hands the porno mags to his son, if you look real carefully, you can see the son hide one of the covers from the camera with his hand. (00:25:39)
Deliberate mistake: When the villains rampage the White House, the flag's base remains on the ceiling, and the flag pole falls inside the house. So the final scene with Superman carrying the flag and its base as if it had been previously stolen or destroyed, is nonsensical, but it looks very patriotic indeed.
Deliberate mistake: After Perseus and his men defeat the scorpions, Kalibos goes after him, lashing his whip. But curiously, the whipping leaves no visible marks.
Deliberate mistake: Despite it being demonstrated multiple times earlier in the film that vampires do not have a reflection, a key moment features the undead Mina being revealed in a reflection in water. The filmmakers said they were aware of the discrepancy but ultimately decided the visual was striking enough to bend the rules for.
Deliberate mistake: Mitch carries Annie's body into her house through the front door, which he doesn't close behind him. In the next shot as he leaves the house it's been closed and he has to open it before he walks out. (01:32:20)
Deliberate mistake: Jack Lemmon looks at his watch as he puts his thermometer in his mouth, and when he takes it out. Obviously in 25 seconds a 1960 mercury thermometer would not give a reading of his 101 fever, it's deliberately done for the scene to move on (although it could have been done differently, with a cut or having him retrieve the thermometer later, since the scene is static and lasts much longer, enough for a real thermometer to work). (00:19:20)
Deliberate mistake: As Rosemary is prepared to be raped by the devil she is lying on white sheets. In the next shot as she is being raped she's on black satin sheets. (00:47:30)
Deliberate mistake: When Harry is seen stepping outside of his hotel the evening after he arrives in Paris, behind him is the familiar Eiffel Tower gloriously illuminated against the night sky. Frequent Paris visitors or residents might recognise the hotel as the Plaza Athenee - to see the Eiffel Tower from there you'd need to be looking in the opposite direction from what we're shown.
Deliberate mistake: When Napoleon asks the school secretary if he can borrow the phone, she pushes the phone toward him but in the shot of Napoleon you can see the phone never actually moved from before he asks to borrow it to the time he makes the call. This is only seen on the full-screen version of the film. The phone is not visible on the wide-screen version because the bottom portion of the image is cut. (00:07:00)
Deliberate mistake: In the scene where Alicia Silverstone and Dave Foley are in the porno store, they cut to a guy standing behind a counter. All of the explicit shots of the videotape covers on the countertop are blurred out.
Deliberate mistake: When the house is splitting in two, the board game should have fallen long before it actually does. (01:25:25)
Deliberate mistake: The soles of the boots Daisy the cow is wearing have been removed to allow her to walk properly. In some shots, their lack of soles is evident.