Continuity mistake: After Ali has thrown his chain at the PM and is heading back to Ricky and Dave, he bends to pick it up. In the next shot of the PM, you can still see the chain.
Other mistake: When Ali drops the green into the teas of the world leaders, the sign on the bag (that submerges him later) is not present.
Suggested correction: It's literally there.
Continuity mistake: In the scene where Ali is changed to the railings, his pants are down. A middle-aged woman comes over and hits his manhood. Obviously he is naked from the waist-down, but in the scene straight after you can just about see Ali's trousers at the bottom of the screen.
Continuity mistake: When Ali and David fight, the alignment of the gun put onto the desk changes between shots.
Deliberate mistake: At the end when Ali smokes the huge spliff, look in the difference in length between when he first lights it and starts smoking it and when he starts blowing the smoke out. It's about 10 times smaller in the second shot.
Revealing mistake: When Ali G's "dodgy rail" is being polished, and David Carlton sees this from the window, it looks as though there is a dummy standing in for Ali G.
Factual error: At the end of the film, Ali is sent to the British Embassy in Jamaica. As Jamaica is a member of the Commonwealth, the plaque should say "British High Commission", not "British Embassy". (01:15:35)
Factual error: When Ali goes to see the Queen for the first time the voice over says "Her Majesty the Queen," while showing the outside of Buckingham Palace which implies that the next shot is of them inside. There is one problem here, the Queen's Royal Standard is not on the top of the Palace which it should be if she is there.
Plot hole: The fact that David becomes conscious after being hit and left back is dramatically fine but there is no aftermath - he misses to finish dealing with Ali and friends at that point.
Continuity mistake: The remote control of the hi-fi teleports between shots when Kate visits Ali at home. Ali leaves it next to the wall (along with the other remote), but it's not there anymore when Kate gets the remote of the telly some shots later.
Factual error: The set of the House of Commons used has only 4 rows of seating. The actual House has 5 rows.
Continuity mistake: Before Ali G gives up his hunger strike he takes a bite out of the chicken piece and the reporter puts it back into the box. In the next shot the reporter puts the chicken piece back into the box again.
Continuity mistake: When the fit refugees are shown to be examined upon their arrival at Dover, the officer in the background is seen to be turning towards the entry door twice during the subsequent shots.
Continuity mistake: Just after the Conference where Ali drugs the world leaders, he is in the car with the Prime Minister. The car drives a good distance beyond a large statue on the left of the screen and yet when the shot cuts to in inside the car they go past the same statue again.
Continuity mistake: In the scene where Ali walks to the floor of the House of Commons, he walks past Charles Dance and Michael Gambon and they say something like "What is he doing..." Look at the guy next to Charles Dance, he has his right hand on his face but immediately in the next shot he is gesturing with it and waving papers with the other hand.
Continuity mistake: When the PM shows Ali the red button, the alignment of the newspapers on his desk changes between shots.
Continuity mistake: In the scene where Ali is at the center with the kids, he gives some yellow stickers to one of them and the kid sticks them to his arm. But in the next few shots the stickers keep changing their position on the kid's arm.
Factual error: The first newscast about the African incident displays Burkina Faso as "Burkina" on the map. This shortened name is not used for this country (AFAIK).
Suggested correction: It says Burkina Faso but it's cuts it off because of the angle at which the camera is filming.
Factual error: When Ali is chained to the fence and the journalists are eating chicken at him, they have a KFC box and mention "Chicken Dippas" but the product they are eating has never been made by KFC.
Continuity mistake: When Ali G knocks the evil Charles Dance out with his chain near the end of the film, one shot shows him throwing it at a low angle then in the next he is throwing it high into the air. (01:11:37)