Doug and the Yard of Doom / Doug's Garage Band - S3-E12
Continuity mistake: Doug's Garage Band: When Doug and Skeeter are performing their song in Doug's room, the trash can being used as a drum and lid being used as a cymbal are gray. When they finish playing, they become black. The handle on the lid on the trashcan also disappears. (00:13:55)
Doug and the Yard of Doom / Doug's Garage Band - S3-E12
Other mistake: After the "Think Big" number, Doug writes an idea down in his journal. There are a brief couple of shots where the edge of the animation cel is visible. It is a white line that disappears.