Cheers

A number of things could explain Rebecca's change - she has not always had a lot of confidence, for one, so after a few tries may have decided it couldn't happen.

Sam throws the ball and it lands in Norm's beer, but when Carla sits down with him, he has the ball again.

Rebecca spent a few episodes trying to buy the bar because it was someplace she felt happy, but suddenly she's reverted back to her old desires to be part of a major corporation.

When Sam goes to the bathroom to check on Fredrick, he turns off the TV. But when he goes to the window, the TV is on again.

Rebecca says she has been at the bar for "5 years", but it has only been 4.

I believe they skipped over a year to hasten Robin's release from prison to end that substory.

Response: That was 5 episodes ago. Paul could have gotten a job as a toll booth attendant between that episode and this.

In this episode they say that Paul is a toll booth attendant. But in the episode "Crash of the Titans" he says that he is unemployed.

In "Adventures in Housesitting" Frasier also walks up and pets Satan when Woody has him in the bar.

Frasier says he's scared of dogs. However he wasn't in previous episodes (he even owned a dog, Pavlov, in "Diane's Allergy"), and he isn't scared of Eddie in Frasier.

Sam prepares a chart on the bust size of previous Boston Barmaid Winners, showing a significant drop for the year of Diane Chambers' victory. However, his chart contains an error - the chart indicates that Diane won the contest in 1984. In fact, Diane won the contest in 1983.

Before the credits, you can see clearly the same black & white picture of Sam that has always hung behind the bar. However, after the credits the picture has inexplicably changed to a color photo in a different pose with a new frame.

It is mentioned Sam never missed a Valentine's Day with Lauren but he was in a serious relationship with Diane on Valentine's Day and was also married before Diane so there is no chance Sam could have gone all 20 years without missing 1 year!

Goof: At the wedding, Sam brings in a pizza box and shows Rebecca a pizza from the night before. About a half of a pizza can be seen in the box. Sam then leaves to get Rebecca's garter and the box of pizza is open and being held sideways by Sam. The pizza would have slid out of the box, but it didn't.

Further support of this: In "Truce or Consequences", Coach states that Gino is the youngest of Carla's 4 children.

Gino is said to be the eldest of Carla's children in this episode, yet in previous episodes Anthony has been the eldest.

Sam learns from John Hill that his Corvette has been towed for parking in John's space. Sam gets mad and tells John that his customers can no longer use "Sam's stairway" going up to Melville's. John then makes an announcement to the patrons of the bar that he is offering a free drink to all customers of Melville's. Everyone then gets up and goes up to Melville's using "Sam's stairway."

Goof: When Norm walks in the bar he complains to the gang that they are installing parking meters "up there." This would suggest that the meters are something new to the area. But in the episode Rebecca Redux, 4 episodes before this one, while Sam is going out to get groceries for the bar, Carla gives Sam some change and tells him to feed her meter.

Goof: Rebecca walks to the bar, busily writing her love letter to Robin on a notepad. As she speaks with Sam, she tilts the notepad toward the camera. We can see it is blank.

In this episode, Norm states he's been going to The Hungry Heifer since college, however, in a recurring storyline in season 3, Norm mentions a new restaurant that just opened, The Hungry Heifer and his ongoing adventures there.