Other mistake: After Frank releases Dr. Scott from the Triple Contact Electro Magnet, Janet and Rocky are heard giggling in Rocky's birthtank. As Frank walks over to the tank, the right magnet pops out again just before it goes off-screen. (01:02:45)
Other mistake: It's revealed that the Knights who say Ni can't say "it" (at least, after they become the Knights Who Say... that other thing), but they still say "it," most notably when they're telling Arthur to place the second shrubbery next to the first one - "When you have found another shrubbery, you must place IT here, beside this shrubbery..."
Suggested correction: They aren't the Knights Who Can't Say "It" - they are the knights who are determined to be a pain in the **** regardless. They are going to be as big a nuisance as they can to anyone who comes along and pretending they can't say "it" is just their latest tactic.
Other mistake: Bobby, Clovis and Celia Bradley find a large gold nugget in a mine. An assayer says gold is worth $15 an ounce and values the nugget at $87,425. That would mean it weighs 364 pounds, more than double the weight of the record-setting 173-pound gold nugget found in 1869 in Moliagul, Australia.