Continuity mistake: Real 4-3: Baby Face/Mr. Right: When Timmy first finds the place in the license plate maker where you stick letters in, there were 7 slots, but later when we see him spelling "I wish I was ten", there are 12 slots, enough to fill in that sentence, without the spaces.
Continuity mistake: Chester is on the tree branch and we hear Timmy say, "This is a list of stuff I'll need for the party tonight." Then there is one poof, and Timmy's room is filled with stuff. In A Wish Too Far, Timmy says the thing about the list of stuff, and then he says the things on the list out loud one at a time, and each time Cosmo and Wanda poof in stuff.
Continuity mistake: In the episode "Odd Jobs", when Timmy's dad is a racecar driver he nears the finish line, his car explodes, and he goes flying, landing within inches of the finish line. However, at the next shot of the cars driving across the finish line, Timmy's dad is now lying a number of feet away.
Continuity mistake: In "Mighty Mom and Dyno Dad Meet the Crimson Chin" Cosmo states that the Crimson Chin comic book has been around since the 1920's, yet when all the Crimson Chins come to help there is no 20's Chin, it starts at the 30's.