Corrected entry: In the scene where the martians invade the White House, just before the First Lady is killed, the President turns around and says "We've lost Natalie." In the movie, his daughter's name is Taffy, played by Natalie Portman.
Corrected entry: Kessler says during the TV interview that the reason the Martians went undetected by the Mars probe is that the probe didn't investigate the very deep Martian canals. There are no canals on Mars - the appearance of lines on the surface was caused by the faults of early telescopes, extensively documented in the 19th century and extensively debunked in the 20th. (00:18:35)
Correction: The movie is a spoof of the 1950s sci-fi B movies, just set in modern times. In the 50s they still believed there were canals. You could add that since there are no Martians on Mars, that is a factual error too.
Corrected entry: 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.
Correction: They are American M-48 tanks.
Corrected entry: When Ritchy is taking Grandma back to the home, she says that she wants to see Slim, Muffy, and Ritchy. Ritchy then says, "Grandma I'm Ricky". He says Ricky not Ritchy.
Correction: Ritchie is short for Richard, as is Rick, Ricky, Dick, Dickie, etc etc. She has her own pet name for him - not a film mistake.
Corrected entry: In the scene where Pierce Brosnan is on the TV show the aliens attack and he stands up. You can briefly see bubbles coming out of his pipe just before the camera changes views.
Correction: Obviously this would have to be deliberate - someone would have to put bubble solution in the pipe, and Brosnan would have to know about it. If the pipe is a dummy (Pierce Brosnan does not smoke) why not use an empty pipe? Not a mistake.
Corrected entry: When the president shouts at the major (Rod Steiger) the clipboard is under his arm. After the president has shouted the major picks the clipboard up off the table.
Correction: he put it down then picked it up.
Corrected entry: When the Martians first come to earth, the ambassador speaks Martian and the computer translates it into: "Greetings. I am the Martian ambassador." But much later in the movie, when the martians are attacking Las Vegas, a Martian says the exact same thing as the ambassador, and the nearby computer translates it into:"Don't run. We are your friends."
Correction: The computer translating the same Martian phrase into two totally different English phrases isn't a mistake at all; the translating computer doesn't work and its operator doesn't know what he's doing. He thumps the computer at one stage, and at other times aimlessly fiddles with the controls, losing his temper as he does. That's one of the comic elements of the film, not an error.
Correction: No, the President says "We've lost Taffy".