Continuity mistake: After Mark is found, he runs into Kate's arms and hugs her and her sunglasses fall off her head, but then in the very next shot they're back on her head perfectly. (01:24:50)
Plot hole: Lucy jumps from the airliner and flies her hang-glider straight to Eduardo/El Macho's Cinco de Mayo party to find Gru. How did she know Gru would be there? He had no intention of going and only did so after he was pestered into it by the girls on the very night of the party, so he couldn't have told her himself. Shouldn't she have gone to his house instead? (01:09:50)
Continuity mistake: If you look carefully at the monster (Frankenstein) you will see that his face is different in the ending scenes. The reason is, during the movie you see the monster take the woman doctor and throw her out the laboratory window. You then see the monster kind of stumble, which he really did and broke his ankle. So in the final scenes they replaced Lon Chaney Jr. as wolfman with a stuntman, and Lon Chaney Jr. finished the movie as the monster.
Factual error: During the war games they have Jefferson pose as a major in order to facilitate the commandeering of the ambulance and the jeep. Regardless of their personal feelings in the matter the ambulance crew and the driver and troops in the jeep would be perfectly aware that no black man would ever be promoted to a position of authority in an otherwise all white command. We may find it repugnant today but the US Army was rigidly segregated during World War 2 - and it stayed that way until 1948. Jefferson may have been inducted into a special unit like the Dirty Dozen but considering that the future of the entire mission is riding on their success at the games, throwing it all away like that makes no sense at all.
Revealing mistake: When Carl is being dragged away by the demons, you can see the cable line that he's attached to. May be fixed on DVD.
Continuity mistake: When JB dreams about singing "Master Exploder" in the small bar, he points at one guy in the audience and literally blows his mind. When he starts pointing you can not only see JB's face, but also how his elbow is in a slight angle. In the next shot the camera shows the guy JB is pointing at and his elbow is completely stretched. The views change several times and the angle of his elbow changes after every cut, until the guy's brain is finally blown out.
Continuity mistake: During Andy's daydream at the beginning of the film, Mr. Potato Head has an eye patch over his left eye. When the daydream cuts back to reality we see that Andy has removed Mr. Potato Head's left eye to symbolize the eye patch. But when Andy's mum comes in with the video camera, his left eye is suddenly back in. (00:01:15 - 00:05:25)
Factual error: When Amy is fired from S'Nuff magazine she takes her story on Aaron Connors to Vanity Fair, who run with it. That is not going to happen. Amy wrote the article while a paid employee of S'Nuff magazine and that means the copyright in the article (and, very relevant to this issue, the photographs of Aaron they paid to have taken), resides with them, not with her. It isn't hers to sell. No magazine editor of any standing is going to buy an unsolicited article without checking its provenance backwards and forwards, and that would mean checking with Amy's previous employers - after all, what would happen if they changed their minds and ran the story themselves?
Revealing mistake: During the bedroom scene with Felicity and Fat Bastard you can clearly see the air hose that fills his suit when he rolls over in the bed. (00:49:10)
Factual error: At the very end of the film Bruce is reporting on a drive for blood donors, and Grace leads him over to the booth to give blood himself - he is even wearing a tourniquet. However, he is supporting himself on a walking stick - he is not fully recovered from the injuries he received when he was run over, which happened when he was hit by a moving car - injuries which left him clinically dead. There is absolutely no way that a person who has suffered life threatening injuries and has undergone the (inevitably) intensive drug therapies and surgical procedures involved while under treatment in hospital in the fairly recent past would be allowed to give blood. There is no way that the Red Cross (or the US equivalent) would want to encourage people who have recently been hospitalised to try to give blood. Not only would that be the height of irresponsibility, they would be wasting precious resources and staff time turning away people who would not be allowed to give blood.
Factual error: It is not possible to be "allergic to all known anaesthetics". Amongst the amide local anesthetics lidocaine, prilocaine, bupivicaine, mepivacaine and dibucaine are naturally occurring substances and if administered without a preservative they cannot trigger an allergic reaction. If Bales is allergic to them, he'd be allergic to the metabolic processes of his own body. They are all powerful local anaesthetics and could easily be used for a radical rhinoplasty such as that required by Bales.
Continuity mistake: There is a scene where the Chipmunks and Chipettes are singing the song "Girls of Rock and Roll." In that scene, it shows the boys walking up the stairs together and from left to right the order is: Simon, Alvin & Theodore. The shot goes to the girls then back to the guys. The order of the guys has switched: (left to right) Theodore, Alvin & Simon.
Audio problem: In the scene after Reese Witherspoon and Luke Wilson are returning from questioning the ex-wife of the murder victim at a spa, they are driving up in Luke's car. You can clearly see, as they get closer to the camera, that what you hear Luke saying isn't what his lips are saying. It was a very obvious dub over...and a very bad one.
Visible crew/equipment: After Josh tells Cher she's such a brat, at the start of the next shot which is the first close-up of Cher during the driver's test, just as she says, "I had an overwhelming sense of ickiness, even though I apologized to Lucy," the top of a crewmember's head, with his short wavy hair blowing in the wind, is reflected at the bottom of the Jeep's windshield, directly in front of Cher and the steering wheel. (01:11:55)
Continuity mistake: When Uma Thurman visits the radio station for the first time, she asks Janeane Garofalo if she can sit down by the microphone. As she's standing in front of the desk she's wearing a cardigan with a handbag over her shoulder. When she turns round to say "you promise not to laugh?", the cardigan and bag have disappeared. (00:16:10)
Continuity mistake: During the Xmas day scene, Markus receives a Sony portable CD player as a gift from Will. However, before the gift's unwrapped, the Sony box is visible on the table. (00:51:45)
Continuity mistake: In the first film, it is mentioned several times that Kevin is 8 years old. However, in this film it is stated that he is 10. When his parents are in the Miami airport security office, they say that he was left alone last Christmas. That would make him 9. Both films take place the same days, from about three days before Christmas until Christmas morning, so even if Kevin is born around Christmas time this is still a mistake.