Visible crew/equipment: After Steven and David return, when President Whitmore walks over to David reflections of the reflector screen are visible on the President's sunglasses.
Continuity mistake: When Major Mitchell gives the crash course to all the new pilots, his hair his much shorter than in previous and following shots, and Russell's beard is also much fuzzier than it was in the previous shots, etc. (01:51:30)
Visible crew/equipment: On bended knee, when Jimmy opens Steven's gift box with the ring, in the close-up an oblong metallic object is pushing up against Jimmy's left hand, between his thumb and index finger. Likely used to keep his hand steady in the tight close-up. (Only visible on fullscreen DVD.) (00:35:20)
Continuity mistake: When President Whitmore boards the chopper and then Air Force One, he wears a white shirt with both thin and thick stripes. The stripes on his shirt collar constantly change, and nowhere is it more noticeable than when they arrive at Area 51. It varies between only one thick stripe, which changes from the top of the collar to the bottom, or two or more thick stripes, all surrounded by thin stripes. Wardrobe Dept bought identical shirts for the actor to wear, but the collar stripes just don't match up between scenes.
Continuity mistake: When Russell boards the F/A-18, he places the photo of his kids beside the left DDI on the instrument panel, which is to the left of the number key pad, below the HUD. When he says, "Payback's a bitch..." there is an upside-down matchbook cover (with the words, "Amraam armed....is off" scribbled on it) exactly where the photo was - beside the left DDI, but then later the photo reappears. Also note that the yellow/black zebra marker behind the photo becomes a blue marker as well. (02:09:10 - 02:13:30)
Visible crew/equipment: When the alien is inflicting pain upon President Whitmore telepathically, in the shot from inside the lab facing the outer hall, through the glass, General Grey's mark is visible on the floor. (Only visible on fullscreen DVD.)
Visible crew/equipment: After the President and the rest return to the containment lab to see the live alien, when Major Mitchell is standing in front of the smoke filled lab, a piece of equipment is seen moving about at the bottom of the screen. (Only visible on fullscreen DVD.)
Continuity mistake: Close to the beginning of the film, when we see the President in the White House, someone turns on the TV. In this shot, there is a chair beside the TV, but when it cuts to an overhead shot, the chair has moved itself to a few feet away. (00:15:35 - 00:16:30)
Revealing mistake: The following take place in F/A-18s. After Jimmy says, "I got you covered, big daddy," there is a close-up of his gloved hand as his thumb presses the launch button. Later, when President Whitmore fires his last missile (with negative impact) there is a close-up as his thumb presses the launch button, and then a minute later there is a close-up of Russell's hand as he presses the launch button (resulting in launch failure). The last two close-ups are the very same shot as shown earlier, only the last two shots are flipped the other way. (00:57:25 - 02:04:00)
Visible crew/equipment: After President Whitmore decides to go ahead with David's plan for the virus, he, Connie and Grey are walking when the President pushes Nimzicki up against a desk. Just before they reach that desk, the actor's mark is visible on the floor, precisely where the President stops before he fires Nimzicki. (Only visible on fullscreen DVD.)
Continuity mistake: Julius and David are driving in the Plymouth and when they reach DC, the car's rearview mirror is visible from the back, but in the next close-up as they pull up in front of the White House gate, the rearview mirror has vanished.
Continuity mistake: When David is explaining to the President about the aliens' intentions with Earth's satellites, he draws two lines that start at the destroyer and go off straight both edging off Earth. But when he places the paper back on the desk to draw in the satellites, the left lines have risen away from the Earth. (00:41:00)
Continuity mistake: On the television screen that has a map of where all the ships have landed in the Eastern Hemisphere, every city is identified by name, except for Berlin, which is just identified as "Germany." (00:26:50)
Trivia: Just after the first building in LA blows up, there is a close-up of a guy putting cash in a case and he's blown backwards in the blast. This is Volker Engel, the film's visual effects supervisor, who won the Oscar for Best Visual Effects for this film.
Visible crew/equipment: When President Whitmore is on the phone with his wife (their daughter Patricia lies on the bed), telling her he wants her to leave LA and a chopper will take her to Nellis Air Force Base, a Secret Service Agent appears at the doorway and the actor's mark is visible on the floor. (Only visible on fullscreen DVD.)
Visible crew/equipment: When Steven is about to leave for El Toro, just as he walks up to his red car, where Dylan plays, the actor's mark is visible on the ground before he steps up to it, and before Jasmine joins him beside the car. (Only visible on fullscreen DVD.)
Continuity mistake: At the Oval Office, when General Grey says, "They're tracking another one off the California coastline," the grandfather clock is perfectly centered between the two doorways. In the following shots the clock is much farther to the right. (00:14:45)
Visible crew/equipment: When David introduces the idea of a virus, the first time Major Mitchell shoots at the Coke can the two actors' marks are visible on the floor in front of Julius and Connie, as well as a brown rug at their feet, that are not in other shots. (Only visible on fullscreen DVD.)
Visible crew/equipment: At the club, when Jasmine walks to the mirror in the dressing room her tape mark is visible on the floor. (Only visible on fullscreen DVD).
Visible crew/equipment: A few shots after the White House and chopper are destroyed, when a light colored car lifts up from the bottom left to top left of the screen, the roll cannon is visible under the car, between the front tires. (00:52:10)
Answer: This is indeed a mistake. The character is played by Bill Smitrovich and is listed as playing Captain Watson, but in the briefing scene he is wearing collar insignia for a Lt. Colonel.
lionhead