Doug's Servitude / Doug Rocks the House - S3-E2
Continuity mistake: Doug is building a house out of playing cards at the end. He has a deck next to him he's using. When porkchop destroys the house, the deck of cards disappears.
Doug's Cartoon / Doug's Monster Movie - S3-E8
Continuity mistake: There is a person holding a sign next to Judy. It says "No censorship." This sign changes. The word spacing is different in the closer angle. In the wide angle there is a noticeable space between the word censor and ship.