Mammoth Studios is a local motion picture company. Two employees, the casting director J. D. Broderick and the filming director Bill Patterson, bring the gang's dog, Rover, in for a screen test and try to direct him when they need a trained dog to do tricks. Unfortunately, neither they nor the gang can get Rover to bark on cue. Another performer for the studio is the ventriloquist Professor Ventriloko, who has some fun making Rover appear to talk.
A sign on the door indicates the full name is Mammoth Picture Studios, Inc.