Continuity mistake: Even though the second shuttle takes off later then the first, they are neck and neck when they clear the atmosphere.
Continuity mistake: When the two shuttles are trying to land on the asteroid, the shuttle Independence crashes, and it is shown crashing upside down and sliding across the surface of the asteroid. Later, having survived the crash, AJ and the Russian are outside the shuttle and it shows it sitting on it's belly, right-side up, with the words United States visible. How did the shuttle suddenly flip itself upright when moments before it was upside down?
Continuity mistake: When the astronaut Sharp comes to his senses and decides to disarm the bomb while it is counting down, the digital readout is just all wrong. Bruce Willis is talking to him and the time reads 40 seconds left. After a good 20 seconds of talking, he starts working on the bomb with a screwdriver and the time reads 35 seconds. Next time we see it, it reads 30 seconds, then when the cover that holds the timer is removed it looks like it reads 45 seconds.
Continuity mistake: When Stamper is banging on AJ's door, a fan and about six cans are on the shelf. In the next shot, the fan has fallen off, but there are only three cans on the shelf.
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: 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: 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 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: 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: 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.
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.