The Peruvian Puff Pepper - S3-E2
Character mistake: Drake says he hasn't been in Megan's room since he was five, but he brings Grammy's bags up there in the episode "Grammy".
The Purple Panther: Part 1 - S3-E6
Character mistake: In the song 'The World Goes Round', Stingy sings about dinosaur bones from the Stone Age (the second verse). The dinosaurs were wiped out about 65 million years ago while the Stone Age started 2.5 million years ago, an obvious time gap.
School Elections & Talent Show - S1-E8
Character mistake: There is a campaign poster that reads, "Vote for Ned or Your Dead." "Your" should be spelled "You're."