Continuity mistake: When Steven arrives on the Sun Incinerator, he's carrying a large sub (sandwich), which he gives to Lars. After the ship's power goes out shortly thereafter, the sub has vanished.
Continuity mistake: The package Steve received from Mailbox is briefly visible before Mailbox comes in. You can also see a crew member's hand holding the package as Steve grabs it.
Spider's Little Daddy/Tricycle of Terror - S3-E1
Continuity mistake: Mandy's working on her report. The page she's on says "CORN by Mandy." A moment later, she writes the same title on another page.
Continuity mistake: When Dum-Dum cuts the rope releasing Chug-a-Boom from the balloon, we cut to the car and you can see Clyde and Dum-Dum are surrounded by the rest of the Ant Hill Mob, but when we see the two in the next shot, the other members are nowhere to be seen.
'Unmei no sentaku' mitaina - S1-E6
Plot hole: Akito's attack is point blank, on a ship part of a fleet with Distortion Field activated (basically, they have shields, like the good guys' robots). The explosion he causes is according to Ruri's damage report big enough that it managed to vaporize 80% of the ships they were facing, but his Aestivalis and the other 3 right floating nearby make out of it literally without a scratch. (00:05:10)
Continuity mistake: Before Charlie says to Lola "You must double-triple promise you'll never play with it", he places the rocket beside a black box. Later in the episode, when Lola attempts to get the rocket down to play with it, the rocket is now on top of the black box.
Other mistake: In the scene where Yakko, Wakko and Dot are sitting at their desks repeating Miss Flamiel's every word, Wakko is drawn without legs (only feet) during one shot.
Is Lupin Burning... ?! - S1-E1
Other mistake: The logo of the evil organization, Scorpion, contains just a little misspelling. It's missing the R. (00:02:50)
Bug Off/The Crawl Space - S9-E5
Continuity mistake: In Moving Away, Tommy tells the other Rugrats how they first met when Angelica lied about the nasty things they did. However in the Crawl Space, there is a flashback of Tommy, Chuckie, Phil and Lil playing in the playpen when they were younger. Chuckie is scared of the Jack-in-a-box in that flashback, so the Rugrats could not have met for the first time back then.
Coffee Quest/Phoenix Rises - S1-E18
Other mistake: In Phoenix Rises, when Phoenix runs away, the Big Coffee sign is missing.
Plot hole: In each episode, Emmy, and Max travel to dragon land (often for a long time) without their parents ever knowing. This makes no sense. Their parents would notice sooner, or later that Max, and Emmy always go in, and out of the house, or that it's always quiet in Emmy, and Max's playroom. You'd think Emmy, and Max's parents would get suspicious, and would question their children accordingly.
Continuity mistake: When Lion-O lands after falling down the crevice after encountering the 3-Eyed monster the ThunderCat Logo on his is a red Lion on a black background, in all other shots it's a black lion on a red background. (00:07:30)
The M.O.D.O.K. That Time Forgot! - S1-E2
Character mistake: M.O.D.O.K. refers to Hoobastank as "the Beatles of the late 90's." Hoobastank only released one album in the 90's, and they didn't become popular until after they released their second album in 2001.
Winning Through Intimidation - S1-E15
Continuity mistake: Panik's Metal Guardian can be seen on the field several minutes before he actually plays it. (00:10:30 - 00:13:00)
Continuity mistake: Chris says he is handing Heather the final marshmallow of the night. When the shot changes for Heather to yell at the rest of the team, Chris is holding a full plate of marshmallows.
Continuity mistake: I know that Animators re-use backgrounds but it is painfully obvious that when Keitaro and Narusegawa are leaving the exam results posting they walk in a straight line past the same "Ristorante" three times.
Twilight of the Apprentice - S2-E20
Continuity mistake: Near the end, when Ahsoka runs at Vader, for a split second when he turns around, the part of his mask yet to be sliced off is already missing.
Continuity mistake: In the episode where Fester invents a fabric: When Fester lies down on the parking lot, his head is first pointing upwards, towards a car, then in the next shot he has turned 90 degrees and his head is pointing towards Norman's legs.
Continuity mistake: Scarface suddenly has his chainsaw when he starts fighting Mr. Snoots.
Beauty and the Obese: Part 1 - S1-E1
Continuity mistake: Right after the opening scene where the model suddenly inflates to fat, we are taken to The Tender Loins club where the exterior shot shows a line of people with a bouncer checking each one. In this shot, his arms are down at his side, but then it cuts a close up and suddenly he has his hand lifted to his face looking at someone's I.D. (00:01:40)