Revealing mistake: When Peter is on the trampoline, instead of saying "Peter," Carol says, "Go get 'em, Chris!" and a few minutes later the same thing happens after Cindy has a turn alone, you can hear Greg say "Why don't you give it a try, Eve?" (00:18:10 - 00:19:50)
Revealing mistake: The wall behind Mr. Brady's desk at work is the exact same wall that is in the boys' bedroom.
Lights Out - S2-E20
Revealing mistake: When Peter is on stage at his school for the talent show, Cindy gets into the disappearing lady booth and Peter closes the curtain. He says the magic words, yanks open the curtain and Cindy has disappeared. Look at the top left side of the booth and you can see where the stage curtain is piled up on top of the booth. There is just enough room for Susan Olsen to get out of the booth and then get back in.
Alice's September Song - S2-E23
Revealing mistake: One of the times that Sam comes over to visit Mr. Brady, he comes in through the back sliding "glass" door. There is no glass in the door. You can tell this because when Sam closes the door, to do so, he puts his hand through the areas where glass would be.
Confessions, Confessions - S2-E12
Revealing mistake: At the start of dinner, in the wide shots we can see the table and chairs directly on the carpet. When Carol notices the leaky vase and calls for Alice, in the wide shot as Alice approaches the table, now there's plastic sheeting spread across the carpet under the table, as well some visible tubing under the table, presumably for the water stunt. (00:05:45 - 00:08:15)
The Hustler - S5-E21
Revealing mistake: When Mike's boss, his wife and two other guests arrive at the house for a night of pool, the four guests are greeted at the front door, enter the brick entry foyer, and descend the steps into the living room. As the camera pans to capture the guests entering the living room, the obviously unfinished and unbricked end of the entry platform can be seen in the shot.
Top Secret - S5-E19
Revealing mistake: Bobby and Oliver are building a house of cards on a small platform sitting on the table when all of a sudden the house of cards collapses. The reason: the platform moves by itself. Clearly it was manipulated off-screen somehow. (00:01:20)
You Can't Win 'Em All - S4-E22
Revealing mistake: When Cindy and her parents get home after the television show, just as Carol and Mike walk down the steps the set's unfinished wood can be seen at the edge of the steps, at the bottom right corner of the screen. (00:22:40)
Revealing mistake: When Carol goes to the dress rehearsal, she is wearing one outfit when she is talking to Mrs. Goodwyn, but then when she goes upstairs to the girl's bedroom and talks to Marcia, she is wearing a totally different outfit.
Suggested correction: Carol was talking with Ms. Goodwin during school hours, and when talking with Marcia about it in the bedroom, it was presumably evening. It's possible Carol may have taken a shower in between that time frame offscreen, thus changing her clothes.
The Voice of Christmas - S1-E12
Revealing mistake: Carol's hair is quite noticeably shorter in an almost 'Twiggy' bob. When in the prior episode 'Vote for Brady' it was past her shoulders, curled into a very fashionable bubble flip. Not that she wouldn't have visited the stylist after the campaign. Just a very noticeable difference.
Suggested correction: The episodes were aired out of order, so this episode did not immediately follow the previous episode in production. Plus, this was a Christmas episode and Carol was preparing to sing in the holiday service, which is just one possible reason why she'd change her hairstyle.
The Big Bet - S3-E18
Revealing mistake: When Bobby closes the sliding door behind him, the curtains swing outward and through where glass should be, revealing it to be an empty frame. (00:01:15)