 The staff was able to get the central cast of the American sitcom Cheers , with the exception of Kelsey Grammer , to reunite and guest star in the episode . The staff could not arrange the script to allow time in the episode for Grammer , who already had a recurring role on The Simpsons as Sideshow Bob , to voice Frasier Crane . Ted Danson guest starred as Sam , Woody Harrelson as Woody , Rhea Perlman as Carla , John Ratzenberger as Cliff , and George Wendt as Norm . 
