She Loves Me, She Loves Me Not - S8-E2
Visible crew/equipment: After Jack talks to Larry about the magazine quiz Jack asks Janet if anything's been bothering her, and just as Terri walks out of the kitchen holding the two cans, a crew member's hand can be seen behind Terri placing a bag on the counter. (00:04:15)
Character mistake: Janet is waiting for Larry to deliver her new car and states to Jack that this is her very first car. But 5 episodes earlier in S8-E13 "Itching for Trouble" when Moose asks if they had a football that needed air, Janet says no, but one of the tires on her car are low.
Friends and Lovers (1) - S8-E21
Visible crew/equipment: When Janet gets ready to throw her bouquet, the boom mic dips into view at the top of the screen.
Friends and Lovers (1) - S8-E21
Character mistake: In S5-E15 "In Like Larry", Larry gives Cindy and Janet gifts to thank them for letting him live with them, so Janet gives him a kiss. Larry also kisses both Janet and Terri on the lips at the end of S7-E6 "Opening Night" after showing them Greek dancing. However, in this episode Janet kisses Larry at her wedding, to which Larry says "Janet, that's the first time you've ever kissed me."
Revealing mistake: In the episode "Out on a Limb", Jack leaves Terri in Mr. Townsend's office lobby to keep the secretary busy while Jack is supposed to climb a tree outside up to the window and move from window-to-window to get to Townsend's office. If you look at the window behind Terri and the secretary, you'll see Jack magically walk through the brick wall to get set up for the tree climbing scene.
She Loves Me, She Loves Me Not - S8-E2
Visible crew/equipment: Just before Larry falls off the boat into the lake, a shadow of a boom mic is visible.
Grandma Jack - S8-E7
Visible crew/equipment: Notice the scene when Terry comes out of the kitchen. As the kitchen door begins swinging shut, a mysterious hand (which belongs to a crew member) suddenly appears from offstage to keep the door closed. (00:07:10)
Grandma Jack - S8-E7
Other mistake: Larry entered Jack as "Grandma Tripper" to win the contest since the contest was only open to women. However, since Larry admits he didn't know there would be a bake-off and thought a winning check would just be mailed, then there's no reason to of entered Jack as "Grandma." He easily could have just entered Janet or Terri using Jack's recipe.
Revealing mistake: At the end where Janet and Jack are in the bathroom (off camera, as he is confessing why he took the car), - you can plainly see that the door to the bathroom is a breakaway door compared to the other episodes, - and even in that particular episode. It's changed in the middle of the episode.
Continuity mistake: When the painting of Jack is hanging in the Regal Beagle, the painting is just legs, and not Jack's whole body. In some shots the top of the painting can be seen.
Visible crew/equipment: Near the start of the show, money comes out of the ATM by error. You can see the money waiting in the slot and the crewmember's hand pushing the money out sporadically. It also comes out sideways sometimes, sometimes not and out of different parts of the slot.
Grandma Jack - S8-E7
Character mistake: Jack says to Larry (upon finding out "Grandma" Tripper won the contest), "You want me to dress as a woman?" as if he never did that before and thought the whole idea was crazy - but earlier in the series he dressed as Chrissy in full drag so he's not new to the idea like he made it sound. Larry also dressed as a woman in an earlier episode as well (just for the record).
Continuity mistake: In episode 8-3, they got a new couch. In this episode, the old couch is back. (00:05:01)
Suggested correction: Many episodes in Season 8 were aired out of sequence from how they were actually filmed. The production code for this episode was 801, and the code for the episode where they got their new couch was 804 (made 3 episodes later - even though it was actually aired first).
Factual error: Jack takes Cheryl's phone off the hook and puts it down, but while the two are talking throughout the two-minute scene, the phone does not make the loud annoying buzzes that occur after 30 seconds or so from the phone being off the hook (which happened back in the years the show aired).
Suggested correction: It could have been a quick comeback line as a joke. The way Janet was even saying it sounded that way. Also, technically speaking, she did have a car in the past. The trio had bought Roper's Car for a very short time (from an earlier episode) before Roper bought it back from them. Janet never physically drove it but at that time, she was ⅓ owner of it so technically she had a car before.
Yes, I always thought it was a quick comeback.