(WARNING: Major spoilers abound!)
In his autobiography, Chaplin claimed that in A Dog’s Life, he brought in the character of the dog Scraps (known as “Mut” on the set) so that his story could contrast the life of a tramp with the life of a mutt. But other than Scraps’ first major scene, in which the Tramp rescues diminutive Scraps from a pack of street-fighting dogs, little is done to enhance that story parallel.
In fact, much of the movie plays like one of Chaplin’s Keystone or Essanay comedies, where he’d start out at a random setting and fish for some laughs. There are many comedy routines in the movie, and some of them are very funny – the Tramp avoiding a cop, sneakily stealing a meal from a food wagon, etc. – but they are no more than routines; they don’t add up to much of anything.
The movie’s weakest section is when the Tramp enters a rundown music-hall and listens to a new singer (Edna Purviance) perform a cry-in-your beer song. The scene’s joke is how Edna’s song moves everyone to tears, but the gag quickly gets very mechanical, if not downright gross – again, something more appropriate for the Keystone era than for Chaplin’s debut at First National Pictures.
The movie doesn’t really pick up speed until the final third. Some crooks have stolen some money and buried it near the Tramp’s sleeping grounds, where Scraps digs it up and presents it to Charlie. Charlie returns to the music hall and promises Edna that he’ll use his newfound wealth to buy them a country farm. Sadly, the crooks are also in the music hall and get wind of the Tramp’s scheme; they knock him out, steal the money again, and get the Tramp and Scraps kicked out of the music hall a second time.
The tramp surreptitiously returns to the music hall and pulls a counter-scheme to get the money back from the crooks. The highlight of the film is the Tramp knocking out one crook and then using his own arms from behind a wall to “act” as the knocked-out crook in order to fool his partner.
Of course, Chaplin got his happy ending, on and off the screen; A Dog’s Life was a huge success and an auspicious beginning to his time at First National. But Chaplin’s next film continued his winning streak while having a far stronger (and more memorable) storyline.