Continuity mistake: In the scene where Sophie is first walking out of the New Yorker building, her shirt is tucked in in the first shot, in the second it is untucked, and in the third it is tucked in again.
Continuity mistake: When the 3 guys are kicking a single guy with Kick-Ass defending him and a bunch of people behind watching the fight, the trashcan on the ground keeps changing positions between shots.
Continuity mistake: When the police car rolls out of the car wash, both passenger and driver's doors are open. When the shot changes to the deputy holding the rifle, the driver's door is closed. In the next shot both doors are open again.
Continuity mistake: When Ray Winstone takes his pill with whiskey while talking to Mel Gibson, he takes a swig of the drink and knocks the pill back, leaving some alcohol in the glass. When we cut to a wide shot his glass is completely empty.
Continuity mistake: When Hiccup first finds Toothless, there is a dramatic shot where the camera pans over Toothless, and his wing briefly obscures his eye, which is open after the wing passes. But look at the tip of the wing. During the shot there is a stretch of rope wrapped around it. In the next shot, the rope is much higher up the wing and not wrapped around it anymore. (00:13:15)
Continuity mistake: On the inspector's boat Frank's wrists are handcuffed together with a railing between his arms to secure him in place. There is a very short chain between the cuffs, 4 to 5 inches at most. When he's pulled free by a rope from Elise's boat he starts 'climbing' the rope hand over hand. In one shot his hands are over a foot apart, he's obviously not wearing the handcuffs. When he gets onto Elise's boat his hands are cuffed once again, she shows him how to pick the locks to get the cuffs off.
Continuity mistake: During the close up of Paul writing the word "Mark White" on the lid of the coffin, he is using his right hand. The shot then goes back to Paul, and he is writing with his left hand.
Continuity mistake: As Darren passes the cheese touch to the girl, she turns around in shock. In the next shot, she is standing still with everyone crowded around her running away, and Darren is no longer seen.
Continuity mistake: When the karate kid first goes to Mr Han's house to train, he drops his jacket by the doorway. Later on as they are talking, you can see his jacket move to different spots on the ground between shots.
Continuity mistake: When Olive is at the ice cream store near the end of the film, she picks up a chocolate-coated cone off the counter and crushes it in her hand. However, in the next shot (as Olive walks away), the cone reappears intact.
Continuity mistake: When the bus passes Poseidon and he disappears, the people walking near him also disappear. There is an Asian couple walking from left to right across the shot that should have been still there after Poseidon is gone. Sloppy SFX that sort of spoils the effect of a god being able to vanish.
Continuity mistake: When Elizabeth meets Lionel for the first time, her face netting disappears and reappears between shots.
Continuity mistake: In the final dance Julien is wearing the samurai jacket, but when the camera changes angles and then focuses back he isn't wearing the jacket. This happens at least three times.
Continuity mistake: When Will has come to apologize and talk to Ronnie after she has left the volleyball game practice, Ronnie's father opens the door to a sweaty suitor. The door is closed and when it is reopened just a brief moment later, Will is no longer sweaty.
Continuity mistake: When Royce kills the Predator at the end, he slices the head off, and it falls backwards, and the body falls forwards. One of the next shots now shows the head to now be in front of the Predator body.
Continuity mistake: When passing the lion in Trafalgar Square approx one hour in, the motorcycle sidecar swaps sides.
Continuity mistake: When Kristi sits down to have her coffee and read her magazine, the coffee cup is perfectly in place before the cabinet doors burst open and she runs away. When she comes back and closes everything, her yellow coffee mug is gone.
Continuity mistake: In one of the final scenes of the movie, George Lopez and his wife are depicted on swings with two red wines placed on a table. The scene transitions into another couple and later George Lopez and his wife are shown again. This time they toast and drink the wine on their swings. However, in this scene the wine they are drinking is white.
Continuity mistake: When Machete is picked up by Booth in the S-class, the car changes from an S500 to an older generation S-class, and then switches back for the rest of the film. The footage was from the trailer being edited in.
Continuity mistake: In the scene when Dalton is climbing the ladder trying to turn on the light in the attic, it shows him stepping onto the same step twice.