Other mistake: When Jennifer meets David in Oregon she says she drove 3 hours to get there. In the next scene they are getting off a bus to catch the ferry. What happened to her car?
Suggested correction: There are possibilities off-screen as to why. It's possible that the bus used its own private road to get to the ferry which may be closed to the public, or the parking lot may have been too expensive and they parked on a street instead and caught a bus. It's not really known, but those are some possibilities.
Other mistake: On the DVD cover, Broderick's and Sheedy's faces and the reflection of their faces on the computer monitor don't match.
Other mistake: When Matthew Broderick is playing Galaga in the arcade, the game ends when he still has 2 lives left.
Other mistake: When David and Jennifer are sat at the IMSAI terminal making the flight reservation for Paris, the date on the booking system shows as 18th March 1982, but the date of the flight is 18th August 1983. (00:29:11)
Other mistake: When David first logs into the system after finding the right password, it shows a phone # beginning with the prefix 936. The only problem was that earlier when his computer was dialing numbers, he had not gotten to 936 yet. That was the 4th prefix and he only got through the first 3. There is no way he could have dialed that number with his computer program.
Other mistake: When David was having his computer dial all the numbers in Sunnyvale, he pulled up the list of numbers already dialled, and there are numbers with the prefix '936', but before he pulled up the list, when the computer was dialling the numbers, the 936 prefix was on the far right hand side. No numbers with the 936 prefix were dialled yet, so they could not have been on the list.