Continuity mistake: There are two scenes during which Harry is shown having visions of the Dept of Mysteries while he is asleep. The first scene occurs after Harry's confrontation with Seamus in the Gryffindor common room. There are shots of Harry lying in bed wearing a short sleeve, crew neck tee shirt, but when he is startled awake by the vision of Voldemort, he sits up wearing a buttoned henley tee. The next day is the first day of Defence Against the Dark Arts class with Umbridge. That last shot of Harry in the henley tee shirt was cut from a later scene. Later in the film, when Harry has the vision of Arthur Weasley's attack, he is wearing the henley tee shirt. (00:34:00 - 01:09:35)
Visible crew/equipment: The scene where Spencer throws the boomerang for the first time and misses the bikers they take off running. While they are running from the bikers, there is a shot right before the boomerang hits the bikers where you can see a camera man sitting in the bushes on the left side. You don't have to pause it, but can to see it better. (00:36:30)
Factual error: During the 31st year of the Avalon's voyage, the ship passes close to the star Arcturus, which is about 37 light years from Earth. Later in the movie, it was stated that the Avalon was moving at around 50% of the speed of light. The ship would not have reached Arcturus in the time allotted.
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: On the ferry, Rachel wears the purple/pink camouflage hoodie over her orange knit sweater with the colorful stripe sleeves, as usual. Now this is where things become strange. In the first shot as the trio come ashore, she is only wearing her orange sweater, she is not wearing the purple/pink hoodie - note the clear lack of fur hood. In the very next shot as they climb a bit more and then rest, Rachel is wearing the purple/pink hoodie - note the hood, but now it's on under her orange sweater. In the underwater shots she is also wearing it under the orange sweater. (This odd mistake has absolutely nothing to do with the very long wool cloak that Rachel wears in the next scene). (01:02:20 - 01:04:40)
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)
Plot hole: At the end of the film Mardukas reveals that he has been wearing a body belt packed with cash - "in the neighbourhood of three hundred thousand dollars" - ever since Jack detained him in New York. Are we to assume that Jack Walsh, an experienced, hard-bitten ex-police officer, now a bounty hunter who routinely chases down violent and armed bail absconders who would kill him without a second thought, didn't even perform a perfunctory search of Mardukas when he detained him? This man used to work for the Mafia! What if he was carrying a weapon? A body belt with three hundred one thousand dollar bills in it would be uncovered by even the most casual pat down.
Continuity mistake: When swimfan85 is trying to talk to Ben and he tells her he has homework to get done, she is talking with the nick name swimfan85 but when she signs off it says "swimfan has signed off." They forgot to add the 85.
Factual error: Then, as now, every recruit reporting to boot camp would be tested for illegal drugs, first by a urine test and then by a broad spectrum blood test in the case of a positive result. There is no reason for Elmo to try to hide his stash when the recruits are told they are to be tested - he is going to come up positive anyway. He may as well just say he has changed his mind and walk away. He is entitled to do that any time up to ten days after he signed on, and it happened a lot in real life!
Continuity mistake: When the real 'manager' comes outside to yell at "Mr. O'Donnell', you see the manager walk back into the club. If you look in the background of the next shot, you can see the manager walking through the door again. (00:13:25)
Plot hole: At the start of the movie, a great deal is made of the boom mic that enters the shot. This is ridiculous, because Bolt's view would not be restricted to what was onscreen, he'd have a perfect view of the person holding the boom mic (as evidenced by it not being stable). There's no possibility of him not seeing the person holding the mic either. As Bolt completely and utterly believes the world he lives in, and thinks the situations he finds himself in (saving Penny) are real, someone holding a boom mic would break the illusion for him. In all instances in the movie where an outside force (i.e. a dog handler) interacts with him, Bolt never gets to see the person handling him (handler approaches from behind), the boom mic operator however is literally right in front of him.
Continuity mistake: He cuts a hole in her pants for insemination. When in the car moments before fighting the dog there is no hole.