Deliberate "mistake": At the end just before the president is killed he fixes his tie, but it keeps on getting fixed to messed, to fixed, etc. Deliberate homage to "A Few Good Men", but worth looking for nonetheless.

Other: When those cute little Martians break into The White House and begin to blast away everything, a few of them get shot in the process. One gets shot in the helmet, and collapses to the ground, suffocating. A few minutes later, during the same scene, another gets shot, and likewise collapses. The animation of the two Martians collapsing is the same, just reversed.

Other: When the general passes the clipboard to the President to sign the nuclear release, the clipboard is actually upside-down.

Continuity: When the martians first visit earth in the desert you can see that the shadow from the poles at the red carpet is on the left side, a few seconds later after the silver ramp is unrolled and the martian ambassador walks down it and onto the red carpet you can see that the shadow of the poles is on the right side.

Factual error: Casey arrives at the desert landing in a jeep that is flagged with 4 stars (for a 4 star general) although he is only a 3 star general (as evident by the 3 stars on his shoulder boards).

Other: In the scene where the President dies, after the General tells everyone to hush and there are agents/bodyguards slowly approaching the door, watch the door to the room before and while it explodes. There are lines in the door which mark the way in which the door will be blown open.

Plot hole: If the president thinks it's so important that the Martians comes to the Congress to present their excuses, why didn't they bring the translating machine?

Continuity: When General Casey answers the phone en route to Pahrump, the helicopters following him drop back in an instant.

Revealing: After the Martian who is dressed up as a women spits a finger in the fish tank a bit of the Martian's mask near its mouth is torn away. As she chews the nitrogen gum the human lips move but her real teeth don't.

Revealing: At the end of the film, when the singer holds out his arm and the hawk flies on to it, you can see the pad under his sleeve that would prevent the talons from clawing the actor's arm.

Continuity: When the press secretary kisses the hand of the alien-dressed-as-a-seductive-woman, the eyeball ring is on her right middle finger but after she knocks him out (or kills him) the ring is on the finger between the middle and the pinkie. In subsequent scenes it's back on the middle finger.

Revealing: The majority of the Army rifles and all the machine guns are obvious props, incapable of even firing blanks. If you watch carefully when they're "firing" you can see that the muzzle flash is actually animated and no shell casings are coming out.  The sound has been added in post production. This is most obvious when the general is firing a havy machine-gun (with no belt) at the saucer over the capitol.

Revealing: When the two boys are playing the shooting game at home, they run away and drop the guns, yet the fish or whatever they are keep on getting blown up.

Factual error: In the scene where General Casey greets the Martians, and the Army is surrounding the event, they have Soviet T-55 tanks painted with American Markings.

Continuity: In the first scene with the Lands, the handles on Barbara's bag continually switch from up to down.

Continuity: When Land is presenting to the investors during the invasion, a saucer flies behind him just as he puts on his hat. In the next shot, that saucer is gone, though there are others still in the background. It didn't move quickly enough to get offscreen in that time.

Other: In the scene where they are at the church, the church looks tiny when compared to the car outside. When the camera shows inside the church it's much bigger.

Other: In the English DVD subtitles, during Jason Stone's reporting at the landing, his line about "many" is mistranscribed "may".

Continuity: The helicopters at the landing site escort the saucer down, then immediately disappear. They are completely gone as the saucer touches down and do not participate in the ensuing battle, even though the Martians are never seen aiming their guns in the air.

Revealing: When Martin Short takes the Martian dressed as a woman into the Kennedy room, he jumps onto a bed which has absolutely no bounce as he lands on it.