excellent example of the way Laurel and Hardy often worked -
they'd start off with a simple situation (Stan has a toothache), follow
it to the next logical step (a trip to the dentist) and continue to a
logical conclusion (the laughing gas causing them to mess up traffic in
the streets of Los Angeles).
Buster Keaton was a big fan of the Boys, as well as a friend and in later years a gagman. There is a scene in the excellent documentary BUSTER KEATON RIDES AGAIN where he enthusiastically describes the second half of this film to a few friends and associates. Describing the minimal plot of Leave 'Em Laughing, Buster concludes "That's all they ever needed was something like that." You can't watch this scene and not feel Keaton's admiration for the Boys.