Visible crew/equipment: When Mrs. Bennett shows up the second time and tells June that she'd like to give Beaver a reward, the curved chalk actor's mark is visible on the floor near the staircase, and it's where June will stand after Poncho and his "mother" leave the house. (00:21:05)
Character mistake: When Gilbert and Beaver are talking to their English teacher in the classroom, the teacher addresses them as Mr. Cleaver and Mr. Harris (as opposed to Mr. Bates). This same name discrepancy is referenced on this site in another episode.
Eddie, the Businessman - S6-E6
Visible crew/equipment: June and Ward are in the kitchen, Eddie leaves and Ward and June continue talking about Eddie and Wally getting hired at the dairy. The next scene shows the exterior of the house, and a dark figure is seen walking from the house toward the garage on the left side of the screen.
Visible crew/equipment: In the opening, the camera boom shadow is visible on the door after June enters and Ward enters.
Captain Jack - S1-E3
Continuity mistake: Where's the puppy that the boys get at the end of this episode throughout the rest of the series?
Suggested correction: In episode 1x23, Beaver and Poncho, when Beaver brings home a lost little Chihuahua, he shows his parents and asks to keep him. Then Ward tells him, "You and Wally had a dog once, remember? You didn't take care of him. We had to give him away." This explains what happened to the dog from season 1, Captain Jack episode.
Other mistake: In the opening, when they get into the car, it's obvious that there is no glass in the rear window.
Other mistake: In season 1, we learn that Beaver is in 2nd grade-Wally in 8th. So by the end of 6 seasons, Wally would be in college. Tony Dow and Jerry Mathers are actually 2 years+/-apart.
Continuity mistake: At the start Ward drives up in their old 1959 Plymouth Belvedere. He had been driving the 1961 Plymouth Fury for some time in season 4.
Deliberate mistake: Although it was done for plot purposes, no school photographer would only take just one shot of a class photo. They generally take up to 15 to 20, as it is difficult to get everyone to look at the camera and smile at once (and hopefully not pull silly faces).
Continuity mistake: In "The Credit Card" four episodes before this one, Eddie uses the $15.00 that Wally pays him from a loan to buy a vest. Later Eddie has to give the vest to a friend in order to get back money owed to Eddie's father. But in this episode we see Eddie at Lumpy's party wearing the very same vest.
Visible crew/equipment: When Beaver works as caddie the second time, the group are at the 18th hole. As Messrs Langley and Howard walk off-screen to the right, the camera crew's shadows can be seen on the actors' sweaters.
Continuity mistake: There are a couple of continuity errors in the dance scene: First, the 4 girls sitting across from the boys switch positions from one shot to the next, then the last girl (long dark hair) disappears from the row of girls entirely, only to show up on the dance floor later in the scene. She was across from (and should have been paired up with) Beaver; instead, the teacher nods toward a now-empty chair and remarks that they "ran out of girls". (00:08:00)
Continuity mistake: When Beaver walks over to the window to look outside, the window is fogged up due to a rainstorm. But when he gets there, the pane of glass he looks through is clear - without his having had time to wipe it off. (00:03:05)
Continuity mistake: When Beaver and Wally are examining Ward's old trunk, two of the pictures of June taped to the inside of the lid go from being a couple of inches apart to right next to each other to apart again. (00:07:05)