Doug Takes a Hike / Doug Rocks - S1-E4
Continuity mistake: When Roger is dancing in Skeeter's yard, he changes color.
Doug's Shock Therapy / Doug Is Hamburger Boy - S3-E11
Plot hole: Doug recalls previous years (in a flashback, where he was next to Skeeter at the window of the Honker Burger as they looked outside) of seeing the Hamburger Boy when Mr. Dink is confessing that he *was* Hamburger Boy. However, Doug has only been living in Bluffington for one year - this was his first summer there.
Doug to the Rescue / Doug's Cool Shoes - S1-E7
Continuity mistake: Doug's Cool Shoes: When Doug is buying shoes, the saleslady takes off Doug's sneaker and when it shows the shoebox, his other shoe is already in there.
Continuity mistake: Patti sings terribly in this episode. But in "Doug's No Dummy", she could sing perfectly.
Suggested correction: While it is shocking, one thing to consider is Patti is going through puberty. It's not just boys who need to relearn how to sing with puberty and can go from canaries to frogs; girls do too. Especially if they have not had proper training, and are aiming for notes they can no longer hit. Patti's at the right age. She may be going through the same thing.
Doug's Halloween Adventure - S4-E12
Continuity mistake: Skeeter, Doug, and Roger are all in line for the scary ride. There are a lot of people behind them. The park closes and the people behind them instantly disappear in a cut.
Doug is Quailman / Doug Out in Left Field - S1-E12
Continuity mistake: The baseball players on Patty's team appear out of nowhere near the beginning. She walks back to the bench in defeat and it's just Doug and Skeeter. A couple of seconds later there are a lot of people in the stands.
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.
Doug to the Rescue / Doug's Cool Shoes - S1-E7
Continuity mistake: Patty's notebook disappears and reappears when she is being bothered by Roger in detention.
Continuity mistake: Patty's hair changes color many times throughout the episode. In some cases it's lighter, in other cases it's the normal color.
Doug and the Yard of Doom / Doug's Garage Band - S3-E12
Revealing 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.
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 Takes the Case / Doug's Secret Song - S2-E1
Audio problem: Around 3 and a half minutes into the episode, Doug, as the Chameleon, says he has a good idea as to who would've taken BeeBe's radio. The end of this sentence is very unnaturally pitched up.
Doug Takes the Case / Doug's Secret Song - S2-E1
Revealing mistake: The framing of this entire episode is such that the edge of the animation cels is visible. Noted on Paramount+.