Revealing mistake: Patty Duke's stand-in is visible behind Cathy when the family is in the front hall welcoming their aunt.
Blue Wants to Play a Song Game - S1-E14
Revealing mistake: After Blue and Steve play the monkeys jumping on the bed game with the sock monkey, when the mail time song plays Steve gets up excitedly and his arm and hand get cut off.
The Bad Beginning: Part One - S1-E1
Revealing mistake: Near the end of the episode when the Baudelaires are in bed, the camera goes outside and pans down the front of the house. Once it reaches the next set of windows below the Baudelaires' "bedroom", the camera wobbles slightly.
Heart of Ice - S1-E3
Revealing mistake: When Batman - disguised as a security guard - opens his utility belt, the belt opens and shows a configuration of buttons and a split-second later, a key card materializes out of thin air in front of the buttons. (00:11:30)
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: 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.
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.
Cruise (1) - S3-E6
Revealing mistake: In the beginning of the show, Shirley is ironing Laverne's clothes and leaves the room. The iron falls on Laverne's clothes on the "L" and burns it, When she picks up the iron, the "L" is on the bottom of the iron facing the normal way when, in fact, it should have been a reverse image.
Exploration - S5-E10
Revealing mistake: When Mrs. McClusky shuts her office door after Mr. Thomson leaves, the walls wobble.
Revealing mistake: Logan gets all the characters to spend spring break at his dad's house. When Zoey finds out Dustin drank all of Quinn's "fratz" she screams his name and runs to go and find him, but despite being meant to be angry you can tell she's laughing.
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 Marco is telling Ellie about getting study candles, the power goes out, but behind them the electrical fan is still running.
Revealing mistake: Obvious studio setting with the fake overlapping grass in the park while Cissy and the boyfriend talk. (00:18:30)
Suggested correction: In which episode does this occur?
Reseda Rose - S1-E6
Revealing mistake: During the meeting on the beach, while Bill remains on the hill Ralph flies to the surfaced submarine, and in Ralph's closeups on the sub the crinkled black set wall behind him is painfully obvious.
The Darkest Hour: Part Two - S4-E2
Revealing mistake: At the very beginning of the episode, as the knights are about to send Merlin to Camelot with Lancelot, the knights walk towards the camera. As they do, there's a patch of green screen the special effects department must have forgotten to remove between Sir Elyan and Sir Percival. (00:02:10)
Revealing mistake: When the robot refuses to let Paul and Barry through, they attempt to go under his arms but they are thrown aside. It is obvious dummies are used, because of their floppy features and blank faces.
Revealing mistake: At the very beginning of the episode, we see a hydrocharge being fired which causes an explosion in the sea. Then just a few shots later, another hydrocharge is fired and we see the same explosion - this is due to footage of one explosion being used twice.
Revealing mistake: During the show when doughnut dressed as a tramp sits on the end of the bench and his weight causes tiger, who is sitting on the other end of the bench, to go up in the air, you can see the wires lifting her.
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.