Audio problem: At the end of the show when Alice is blowing the whistle, the whole family comes to the top of the stairs. Mike says "Alice, it's 6 o'clock in the morning" Watch his mouth. It looks as though he curses and the (curse) word was dubbed out.
Continuity mistake: The microphone next to the tape recorder moves from one shot to the next. (00:26:05)
The Winner - S2-E21
Continuity mistake: When Mike and Carroll drive Bobby to the TV show for the ice cream eating contest they leave in the blue convertible. They return home in the brown station wagon.
Other mistake: The scene where Alice is giving Tiger a bath was the same one used in "Katchoo Katchoo", albeit with some audio dubbing thrown in, like when Alice complains about the floor getting wet. (00:04:05)

Continuity mistake: When Peter comes down to answer the phone, he's wearing a blue shirt. When he hangs up the phone, his shirt color changes to a light red/pink color. Then back to blue again.
Continuity mistake: When Cindy goes downstairs to ask "isn't anyone coming up to say goodnight?" or something similar, when Alice is talking to Mike and Carol about Sam not coming over, Cindy is wearing her pyjamas. She then gets in trouble and goes straight back up to her room and she is suddenly dressed in jeans and a top - her hair has different hair ties in it too.
Continuity mistake: The last line of Alice's recipe, written on the chalkboard, changes from "3 egg yolk" to "3 egg yolks" and back again. (00:06:15)
Is There a Doctor in the House? - S1-E13
Plot hole: Lots of factors here: The doctors end up with the opposite kids that they were supposed to have... Why didn't they simply switch in the first place rather than go through all the drama? Also, the male doctor admits Alice let him in and most likely Alice would have told him first door on the right (like she's given directions in other episodes) to locate Peter. And the biggest question of all is, what doctor would make a house call and not look for their patient rather than just ending up with someone else they were not called to see (remember, each parent called their own doctor to see their biological kid).
Suggested correction: The lady doctor goes to see Peter as Mrs. Brady directs her to Peter's room first. Alice likely knows Peter already has a doctor looking after him, as it can be assumed Carol told her, so she sends the male doctor to Jan's room likely explaining to him that Mike's new daughter is also sick and needs to be checked. As to why they didn't solve this doctor problem to begin with; simply they are still a new family and didn't yet think about this as this is the first time the kids are sick.
Fright Night - S4-E6
Continuity mistake: When Jan, Marcia, and Cindy search the boys' room Cindy finds the slide projector under Greg's bed, and when Marcia holds up the transparency slide with the "ghost" image, the close-up of the slide presents two problems. First, the "ghost" is horizontal in the wide shots, but is vertical in the close-ups, and second, the fingers holding the slide in the close-up do not belong to Marcia.
Continuity mistake: In the kitchen when Jan announces that she took up tap dancing, Mike's first button goes from buttoned to unbuttoned a few times during the scene. (00:06:00)
Continuity mistake: In "Our Son, the Man", Greg wants his own room. One night, while in bed, Mike and Carol discuss their options. Carol says, "How about the attic?" Mike responds with, "That would be fine if Greg were only two and a half feet tall." Later, they give Greg the den for a while. However, in "A Room at the Top", after cleaning out the attic, which was now full size, both Greg and Marcia want it for their own private room.
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)
Visible crew/equipment: When the shelf falls in the store, you can see the rope attached to the top of the shelving unit being pulled from off-screen triggering the collapse of the shelving unit, it was not the girl's weight that made it tip.
Deliberate mistake: While Bobby's parakeet is flying around downstairs, before the bird settles down on the TV set there are two closeups of Bobby which are flipped shots, note the furniture and Bobby's PJs. (00:07:00)

Continuity mistake: At the start of the episode, in the exterior shot when Jan and Peter rush through the patio door Jan doesn't have a ribbon in her hair, but in the interior shot suddenly there's a long red yarn ribbon in Jan's hair.
Continuity mistake: While they're in the courtroom, when Carol is standing beside Harry Duggan in front of the board, the small red car on the board keeps changing from being straight to slanted, depending on the camera angle.
The Not-So-Ugly Duckling - S2-E9
Continuity mistake: When Jan comes home and tells her parents that Clark didn't notice her at school, she's wearing a white blouse with a floral design and a red ribbon in her hair, but when she gets to her bedroom and accuses Marcia, she's wearing a striped blouse and a light green hair ribbon. Then when Jan talks to Greg she's wearing a green tee shirt and a dark green ribbon, but when she asks permission to go to the store she's back in the striped blouse and light green ribbon.
The Treasure of Sierra Avenue - S2-E7
Visible crew/equipment: The set lights are reflected in Greg's beach ball in what is supposed to be an outdoor scene. (00:20:35)
Other mistake: A final contest is given for control of "green stamps" with all the kids building a "House of Cards." Whomever causes the cards to fall will be the losers. All is going well until Tiger comes in and knocks into Greg and causes him to bump the table and knock over the cards. If you watch closely at the end of the scene, when all the dialog is finished, you can see Mike trying to knock down a few remaining cards. However they keep popping up. Probably due to the fact that the cards were glued together to make it easier for the kids to build upon.
Continuity mistake: When the kids are building the card castle to see who would get to choose what they get with the stamps, Jan is putting a card on, in one shot her hair is up in a ponytail then in the other shot her hair is down. This happens back and forth when the shots change.