At Mutual, Chaplin had more freedom, and the result was the funniest and most entertaining short films he ever made. 'One A.M.' is one of his most experimental Mutual shorts: how many laughs can he get from a 20-some-minutes drunken solo, where, for the most part, he only interacts with inanimate objects (although the Murphy bed seems very alive). He got many from me.
Chaplin did a hilarious drunk act--that's evident in many of his other films, as well: 'The Rounders' (1914), a Keystone short costarring an equally funny 'Fatty' Arbuckle, comes to mind, as does another of his Mutual shorts, 'The Cure' (1917). Moreover, Chaplin's tendency to portray a dandy as a drunk, rather than a tramp, which could cause the humour to lose out to melancholic social commentary, was prudent. Making fun of the tacky and ridiculous possessions of an overly dressed bachelor is more of sure thing. Chaplin's dandy--even his tramp personae--owes plenty to Max Linder, too, as Chaplin himself often cited.
Another influence worth mentioning here is his background in Fred Karno's Fun Factory troupe. The only filmmakers other than Chaplin who are provided with much to do in 'One A.M.' it seems are those in care of the props and setting. 'One A.M.' could have as easily have been a music hall act as a short film. Nevertheless, all of this does make for a unique film in Chaplin's canon. By now, it's clear that Chaplin had matured from the rapid-paced, knockabout style of Keystone for a more graceful pantomime. That's not to say there aren't pratfalls and other tried-and-true gags here, but the temperament is radically different.
