Other mistake: The Time Expansion Helmet was supposed to allow Dexter to perform his 30 minute morning task in 30 seconds. Since this is the case shouldn't the cat have hit the fishbowl ages ago as time is not frozen.
Plot hole: I thought the monster was in Japan. How did it end up in America at the end?
Mandark: George, what do you say we cross the Delaware?
More trivia for Dexter's Laboratory