Continuity mistake: When Harry and Chick are lying down and the spinning pillar goes over them, the pillar's direction of spin changes twice. Backward spin, then forward, then backward, then forward again.
Continuity mistake: When Harry is golfing off of the oil rig, the holes on the golf ball are spaced about a yard away. In the next shot, before he hits it, the holes are right together. It also goes from saying just "Srixon" to "3 Srixon," then the lettering gets angled, then he finally hits it.
Continuity mistake: The montages around the world show a boy listening to a transistor radio. In order to make it look truly Americana the boy has an old-fashioned earphone in one ear but continues to hold the transistor radio up to his ear as though the speaker were working in addition to the headphone. (01:03:40)
Continuity mistake: At the beginning of landing shuttles on the asteroid, Col. Sharp, pilot of Freedom, was wearing a black short sleeve T-shirt. At the moment of landing on the ground, he's wearing a flying jacket even not leaving his seat yet. Did he have enough time to put on his jacket during such an emergent situation?
Continuity mistake: When they are drawing straws to see who stays on the asteroid, they show AJ pulling his straw. It's the same length as the other straws shown, but when it cuts back to AJ he all of a sudden has the short straw.
Continuity mistake: When Chick's son recognizes him on television, the camera shows a close up of his ex-wife with the phone in her right hand. However, the next shot shows her dropping the phone receiver from her left hand. (01:04:03)
Continuity mistake: The front of the space shuttle explodes twice. After we see it explode the first time after it first gets bombarded with projectiles, in the very next shot, we see the front half of the plane with two crew members floating around inside at which point we hear: "Houston!". Then the front part of the shuttle blows up again.
Continuity mistake: When the drillers are getting checked out at NASA to see of they are o.k. to go into space, the fat white guy is wearing a robe that is covered with blue dots. The next time we see him, he is in a plain white robe.
Continuity mistake: When AJ bumps into Bear his shirt is very dirty on his right side, but as he runs up the stairs it is much cleaner and has a sweat mark around the neck line. Next shot on the tower and the sweat is not in the same pattern. After he slides down the cable the dirt is in a different pattern again. (00:14:10 - 00:15:00)
Continuity mistake: When Harry goes into A.J.'s room, he gets mad and sticks the end of a putter golf club at A.J.'s throat. The next scene the club changes and is not a putter anymore.
Continuity mistake: When they are boarding the shuttles, Harry and AJ have a brief chat and they get onto to bridge last. But somehow Harry manages to get in front of Rockhound and Max, and AJ manages to get in front of Oscar and Bear.
Continuity mistake: After Harry catches AJ in bed with Grace, AJ runs out of the room. Cut to the next camera angle taken from outside as AJ leaves - and he has a pair of boots tied together around his neck. They were not there in the previous shot. (00:13:00)
Continuity mistake: When the team meets the flight crews for the shuttles, there are two munitions specialists - Gruber and another astronaut. We see this other astronaut board the shuttle, then he's never seen again, not even his body.
Continuity mistake: The first shuttle takes off some time before the second. Nevertheless we see a picture of both shuttles in the air shortly after they clear the towers.
Continuity mistake: Near the end of the film when Sharp says "Houston, we're coming home." We see Bear looking out at the Asteroid passing the Earth yet in the next shot he is strapped to his chair saying "You Harry, you the man". (02:19:55)
Continuity mistake: As Harry's crew is about to start drilling, Rockhound analyzes the surface. The drilling head is already bellow the asteroids surface. When the camera pans back to Rockhound the drill head can still be seen slowly turning on the upper right corner.
Continuity mistake: When Grace throws down Thurman because of frustration, she first grabs him by the back, but in the next shot he's facing upwards. (01:55:25)
Answer: If you look at the deleted scenes on the special edition DVD, you will see a deleted scene in which A.J. asks what they needed a gun for, and Max explains that it's for debris elimination, in order to take out small rocks in the way.