What is... Cliff Clavin? - S8-E14
Continuity mistake: Just before they reveal the answers of Final Jeopardy, they take a wide shot, and Cliff's question (Who are 3 people who have never been in my kitchen) is already revealed. But when they take a tight shot and ask Cliff to reveal his question, it is covered up.
The Ghost and Mrs. Lebec - S8-E23
Continuity mistake: When Carla is talking about seeing Eddie and the restaurant there is someone at the bar who puts their drink down. The shot changes, the drink has disappeared from the bar, and the person puts it down again.
Indoor Fun With Sammy and Robby - S8-E19
Continuity mistake: After Sam and Robin are done playing darts, Sam puts his darts on the pool table. The shot changes and the darts have moved.
Continuity mistake: Sam, Norm, and Woody are helping Rebecca move into Robin Colcord's house. When a curious Norm opens a bedroom door, the wall is bare. The shot cuts to Rebecca then back to Norm, but now there is a desk with flowers and a vase on it, plus a picture hanging on the wall.
Continuity mistake: When Woody gives Norm a beer he puts a napkin next to the beer. The shot changes the napkin is under the beer.
Continuity mistake: During the scene when Norm is giving Doris the letter of recommendation her hair his covering her ear facing the camera. When she says "It must have taken a lot of guts to open up that way." Her hair is now behind her ear.
Continuity mistake: When Cliff walks into the bar and walks over to Norm his beer is almost gone - the shot changes and it's full. (00:17:25)
Continuity mistake: After Frasier leaves to be bad, Norm starts talking. He puts his hands on the bar, the shot changes and he now has one hand on his glass of beer. (00:16:55)
What is... Cliff Clavin? - S8-E14
Continuity mistake: At the point Cliff is disputing the fact that he thought his answer was right, on the right-hand side you can see the woman player's, Agnes, score. It says $400. Then in the next shot it changes to $3300. Then in a little bit later it changes back to $400. (00:14:30)
Answer: Here is the source of the "WE WIN" photo: http://www.oldnycphotos.com/nyny587ac.html Brooklyn, of all places.