Character mistake: In the beginning where Karen is introduced to Andy and Barney in the coffee shop, her name is Karen Worth, then at the last where she is called as winner of the Skeet Shoot her name changes to Karen Moore.
Suggested correction: She is introduced as "Karen Moore". Thelma Lou's pronunciation is a bit off (what she says sounds like 'moor', as in an English moor), but she says "Moore."
Barney Hosts a Summit Meeting - S8-E21
Continuity mistake: In the scene where the meeting participants are in the kitchen, the Russian guy opens the icebox, does not close it, and sits at the table. When Aunt Bee comes in immediately thereafter, the door is closed. She opens it again and partially closes it; but in the next shot, it is fully open.
Suggested correction: The first part of the mistake is correct. However, after Aunt Bee partially closes it, if you keep your eyes on the left side of the screen where the ice box is and watch carefully, you can see the ice box actually bounces back open fully on its own.
Deputy Otis - S2-E31
Other mistake: Upon arriving at the courthouse, Andy and Barney discover they don't have their keys to get in so Andy decides to go knock on the window at Otis' cell, which he does to wake Otis. However, Otis' cell does not have a window, only the adjoining cell does. (00:20:00)
Suggested correction: Otis' cell does have a window. In the previous episode with Barney's cousin, Barney's pulls the window out of the wall to get Otis out. Also in another episode Barney gets an intercom and places one part by the window to demonstrate how it would work.
