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)
Jeff Swanson
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: 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)
Jeff SwansonContinuity 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.
Super Grover
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.
Super Grover 
Deliberate mistake: During Peter's party, when the girls start to gather around Peter to try and convince him that he's not dull, there's a closeup of Peter that's a flipped shot. Additionally, when everyone runs out for the fire drill, Peter's striped tie is tied very differently - it goes from grey/gold at the top to burgundy at the top.
Super Grover Character mistake: In the courtroom, Cindy and Bobby are repeating their fight over spilling ice cream and Cindy says "You spilled ice cream on my dress" but at the start of the episode when coming home from the store, Cindy is wearing pants, not a dress.
Continuity mistake: When Greg and Marcia are taping the fake message for Peter, Greg says, "Bang, he buckles down and brings home an A." But when Peter listens to the message a minute later (16:15), Greg's statement is now "Bang, he brings home an A." (00:14:50)
Jeff SwansonPlot hole: At the end of the episode, the younger kids are singing the song "Girl" that Davy Jones did a little earlier in the show. The problem is that the song was just recorded and hasn't been released yet, they couldn't possibly know the song. Davy gives Marcia an LP, but it is on the same day the song was recorded, it couldn't be on there either.
Continuity mistake: In the photo of the football reception, the enlarged photo is not from the original. The receiver's legs are in a different position. (00:22:35 - 00:23:20)
jairodrigueContinuity mistake: In the courtroom, as Carol is giving the judge her side of the story, she's looking in the direction of Mr. Duggan the whole time while saying "otherwise he wouldn't have hit me." Then the camera changes angles and instantly Carol is turning from facing the judge back towards Mr. Duggan.
Continuity mistake: At the start of the episode there's a wide shot of the house exterior as the Brady's station wagon is pulling into their driveway, and the wagon has wooden side paneling, but in the next closeup the paneling is gone. Plus the fact that the rear-end damage doesn't exist in the first wide shot, which is the point of this episode.
Super Grover Other mistake: Just after Bobby and Cindy get lost, there are shots showing Mike and Carol calling for them. A couple of minutes later the same shots are shown again, but this time they're flipped. (00:22:00)
Jeff SwansonContinuity mistake: When Marcia is sitting on the couch talking with Davy, the small beige pillow behind her is either up on the back of the couch or much further down depending on the shot. (00:23:20)
Jeff SwansonContinuity mistake: When Zaccariah steals the last piece of fried chicken off the plate, the plate is left completely clean, yet when Alice goes to get the piece a few seconds later, there's a sizable grease stain on the plate. (00:14:05)
Jeff SwansonOther mistake: When Jan finds the picture of her Aunt Jenny, we see a close-up of the picture with her hand holding it. She then passes it to Carol - and the same shot of the picture with the hand is shown again. (00:02:10)
Jeff SwansonDough Re Mi - S3-E16
Continuity mistake: During the recording of "Time To Change", Jan's hands are always together when she's shown. But in the shots showing just the boys, look at the right side of the screen and you can see fingers (which have to be Jan's since she's standing beside Peter) moving as if they're drumming on something.
Jeff SwansonContinuity mistake: The kids are in a circle on the living room floor. They're spaced well apart from each other in some shots but right next to each other in others; in particular Greg and Marcia, and Bobby and Cindy. (00:19:00)
Jeff SwansonMy Sister, Benedict Arnold - S3-E5
Continuity mistake: When Kathy Lawrence enters the Brady home, as she walks through the kitchen, her top button is unbuttoned. When she is in the living room cheering, it is buttoned.
Answer: There are a number of photos online of the Brady house's exterior of what it looked like when the show was being filmed and what it looks like today. Only the exterior shots were of a real house. The interior was a studio set and it did not exactly match the real home's floor plan. There are also some YouTube virtual tours of the house that explore the interior. If you Google "Brady Bunch House" you will find much information about this.
raywest