Continuity mistake: When the panel of doctors are being queried by Aames, for the second time of the loop of this interview, the black box containing the mask can clearly be seen in the bottom right hand corner on the desk when the camera swings to the main doctor. When the camera pans back again, it is gone, and it is only after this that the assistant brings in the box.
Continuity mistake: In the scene where Tom and Penelope are lying together on her sofa there is a table to the left with a lamp and some wooden artists figures. These move position between shots, with different things happening with their arms.
Visible crew/equipment: When Tom Cruise is standing alone in the hall at the ground floor of the LE building, screaming for "Tech Support..." the camera pans around him 360 degrees. When the camera pans over Tom's left shoulder, you can see the shadows of the camera crew on his jacket. After the panning has come to a stop, you can see the reflection of two or three crew-members in the glass walls behind him.
Revealing mistake: When David is sitting in L.E. at the end and the camera is zooming in on his face his mask changes. In the very last shot of him just about to pull it off it's much wider/looser so it'll come off easier.
Revealing mistake: During the love scene towards the end of the film, with David and Julie, it is obvious that Cameron Diaz (who played Julie) is only in the bed for her shots. The reverse angle of David shows him making love, but other than a badly-matched wig on the pillow there is nothing to stand in for Diaz. There is no sight of her body or head, and the wig is the wrong color and shape, not to mention it looks like a wig.
Continuity mistake: In a scene during David's birthday party there is a sequence showing Julie and Brian talking on a sofa with a blank white wall in the background. Later, in a different scene showing Julie dancing with one of the waiters holding a tray of martinis in front of the same sofa, there is a black and white picture of a car in the background.
Continuity mistake: In the scene with David's birthday party, he comes downstairs after being with Julie, and is talking with Sofia about how Julie is stalking him, when Julie is staring at them, her part in her hair goes from being on the left side to being on the right side, then back again.
Continuity mistake: In the scene where David discovers Julie in his bed her strap is on her arm. In the next shot it is where it should be.
Continuity mistake: When Tom takes Penelope home, it is dark outside. However, when they go inside seconds later, there is clearly light (and more than just streetlight) shining through the curtains, as if it were day.
Visible crew/equipment: When the camera zooms in on David's car after he's nearly crashed, you can see the camera to the right of the reflection in the window.
Continuity mistake: In the scene where Tom Cruise gets out of jail and has a confrontation with Jason Lee, you can clearly see (towards the end of the scene) that in Jason Lee's shot it is snowing, and in Tom Cruise's it is not, then when it goes back to Jason Lee it is snowing again. (01:32:45)
Visible crew/equipment: When David is about to leave for L.E. there is a very brief shot of him in the back of a car looking out with his mask on. Just above the door handle you can see the dark reflection of the camera.
Continuity mistake: When David and Sophia go upstairs to his friend's apartment, his friend walks in. When he is talking to David in this scene, in one shot David's hair is perfectly normal, and then there is a shot of his friend, but when it comes back to David his hair is abnormally messy and sticking up. In the next shot of David it's back to being flat again.
Revealing mistake: The office of LE is located in the California Gas Tower, an office building in downtown Los Angeles. The movie is set in New York City.
Continuity mistake: In the scene where Penelope is looking at the drawing of her face, she is holding it in her left hand. But next shot (camera behind Tom Cruise's back) shows that she has the drawing in her right hand.
Continuity mistake: When David comes back to Sophia's apartment, towards the end of the film, he rips the photos off the fridge. But in the next shot, when he is throwing something to the wall, the photos are still on the fridge.
Continuity mistake: Tom leaves the bar after wearing the mask in public for the first time. He and his best friend have a argument outside in an alley. As they cut to and from Tom his hair is hilariously out of whack on one of the shots.
Plot hole: The female employee says he's going to inherit everything, he gets it all. No he only gets 51%, the 7 dwarfs still make many decisions. (00:10:37)
Character mistake: It sounds like the person who called him on the cell is not a secretary but also Cameron Diaz pretending to be a secretary. The same voice. (00:07:12)
Answer: I think the one you mean is 'Afrika Shox' by Leftfield & Afrika Bambaataa which is track 10 on the fantastic soundtrack.