Revealing mistake: Right after TJ and friends are looking at the "thermometers" of cans, the Ashleys have at least 4 crates of cans that they bring in on forklifts. However, the end result is 4,362 cans for the Ashleys. This may seem kind of picky, but I think there was more cans than 4,362.
Suggested correction: This is literally just an assumption, and nothing else. 4,362 is a pretty huge number, and with the amount of cans that we see the Ashleys collect in the episode, combined with the amount of cans that they and the rest of Miss Furley's class collected off-screen, it is perfectly believable that Miss Furley's class would end up collecting that amount of cans.
This Male Chauvinist Piggy Went to Market - S3-E1
Revealing mistake: When Laurie goes to flip Goose over her shoulder, it's obvious that a stuntman is actually flipped; he has much shorter hair than the actor portraying Goose. (00:11:45)
Revealing mistake: Angelica and the other children are about to crash through the door to attack Lyra and Will. As Lyra runs past a cabinet, a lamp sitting on top is knocked over and crashes to the floor. Dafne Keene, who plays Lyra, reached over and very obviously pushed the lamp to the floor.
Revealing mistake: The scene where Macduff, Johnson and Diesel are happy because they found Macduff's "button" medal of bravery, watch when diesel jumps up and down. You can the actor's black shoes he is wearing. This also happens throughout other parts of this episode. (00:06:40)
Firefly, Light My Fire - S1-E1
Revealing mistake: Courage winces and reacts before the stereo-zapper is fired.
Revealing mistake: In the song "Living Island", we see Judy frog jumping over Pufnstuf. When she goes back down, the wires holding her up and putting her down are visible.
Revealing mistake: When Marco is telling Ellie about getting study candles, the power goes out, but behind them the electrical fan is still running.
Revealing mistake: A little oversight on the part of the producers. At the final scores that we are shown, Amy has $10,000, TJ has $9,800, and Travis has $2,400. This all adds up to $22,200. Even if they only answered $400 questions (which we can see that they don't), that's about 55 questions at best, only in the first half. That would run way longer, probably about three or four times as long, as any normal game show. And there's no mention of any other rules regarding the scores so there's no reason to think that there are bonus questions that could raise it that much.
Race to the Spaceship/Sandbox Surprise - S3-E5
Revealing mistake: In the sequence where Pig is making a pizza with strange toppings, an ant caries a large bucket of popcorn up the counter. It is flush on its back with no top when on the floor, and the popcorn is bulging out. The ant turns 90 degrees and walks up the counter, and the popcorn thus turns on its side in the air. Not one piece of popcorn falls out or even shifts, despite the pile now pointing out rather than up.
Save the Max - S2-E3
Revealing mistake: When they are reading the reviews in the newspaper, look at the back page. It's the sports section. Next when Jessie comes back to Zack and tells him what Mr Belding was hiding, she says the paper is from 1968. But look at the back of that paper also. They are using the exact same paper. The reviews and the 1968 paper are the exact same.
Revealing mistake: During the opening theme, when the children are watching the magician, you can tell they were not actually filmed together. The magician scenes are filmed more professionally using a sharper tape or film image, whereas the children scenes look more like a standard fuzzier film-type such as on a projector (primarily used at that time).
Revealing mistake: While Beaver checks to see if the paint's dry on the patio table, when the bee appears and flies around him, the wire is visible. (00:19:00)
Revealing mistake: When Andi walks into the library (this is not Andi's dream) it cuts to the librarian sitting at her desk and we can see the shot is flipped - note the bookcase and the librarian's buttons. (00:10:40)
The Cavern - S1-E10
Revealing mistake: When Jonathan and Nicky are running out of The Cavern during the rockfall a cabinet is knocked over by the vibration, but you can see that it is pushed over by someone with a stick.
Revealing mistake: When Roberta Halton knocks Rob unconscious, you can see that the blunt object barely even makes contact with his head.
Revealing mistake: Oliver and Eb cast shadows on the painted backdrop as Mr. Haney drives up.
Lavando el carro del Sr. Barriga - S4-E4
Revealing mistake: When everyone is fighting with the water buckets, Don Ramón (Raymond) throws water at Quico. Doña Florinda (Mrs. Worthmore) chases Don Ramón inside the neighborhood. When Quico was about to throw water at Chavo, inside the door, the shadow of Don Ramón waiting for running so Quico can throw water at his mother. Plus, when Don Ramón and Doña Florinda runs outside the neighborhood, Doña Florinda is already covering herself in the last second before getting wet.
Revealing mistake: When Cissy is at the piano as Buffy sings and dances for Uncle Bill, only her arms move up and down instead of across the keys, indicating that's it's an off-camera person actually playing the tune. (00:16:30)
Full Moon / Student Teacher - S4-E1
Revealing mistake: Student Teacher: When Olga says, "But, nothing, baby sister!" before giving Helga detention, Rhonda and Brainy disappear for one frame. (00:17:17)
Revealing mistake: As Pat Buttram enters the office of the Bugle newspaper, he casts a shadow on the painted backdrop of the buildings across the street. (00:19:30)