MR. MUGGS RIDES AGAIN (1945) is not the first film in the East Side Kids series to cast the group's leader, Muggs McGinnis (Leo Gorcey), as a jockey. Here he runs afoul of Dollar Davis (George Meeker), a local gambler/horse owner, by winning a race he wasn't supposed to and winds up getting disqualified and then suspended from the track when an illegal "buzzer," a device designed to spur a horse to run faster, is planted on his saddle. The rest of the film follows the characters in little slice-of-life neighborhood/racetrack vignettes as the boys rescue a beloved horse from the glue factory and keep him illegally in their tenement basement clubhouse, leading to a confrontation with the police. Eventually, Muggs has find a way to clear his name.
The boys' mentor, Mrs. Brown (Minerva Urecal), a middle-aged horse-and-stable owner, is helped by the boys at crucial moments and she helps them in turn at other crucial moments. Her pretty niece, Elsie (Nancy Brinckman), is befriended by the boys, but is viewed with concern when she dates a local gambler, Gaby O'Neill (Bernard Thomas), who works for Dollar Davis. Gaby was the one who planted the buzzer in Muggs' saddle and Muggs has not forgotten. A key scene takes place at a carnival midway when Muggs' sidekick Glimpy (Huntz Hall) takes the place of a drunken fortune teller, dons his disguise, and reads the future for Elsie and Gaby, making up a grim on-the-spot premonition. This leads to a heart-to-heart talk between Elsie and Gaby and a change in moral direction, resulting in a battle with would-be killers in a hospital room and a last-minute session with the racetrack stewards just before the big race.
The plot is never terribly suspenseful or compelling, but the film is only an hour long and gives plenty of good scenes to Gorcey and Hall. Gorcey's later Bowery Boys character, Slip Mahoney, would adopt a trademark habit of mangling big words ("This was the pinochle of my career"), but Muggs, at least in this film, throws a large vocabulary around quite skillfully. At one point, he describes the harm done to Elsie's "mental equilibrium" by falling for Gaby. Hall's Glimpy is a goofball like his later Sach character in the Bowery Boys, but he's no dummy. He's crafty, streetsmart and a bit of a ladies' man. The East Side Kids, in general, were more defiant than the Bowery Boys, more inclined to mouth off to local beat cops, and more inclined to confront local tough guys.
None of the other original Dead End Kids, aside from Gorcey and Hall, are in the cast, not even Bobby Jordan or Gabe Dell, who were in several of the other East Side Kids movies. Black actor Ernest "Sunshine Sammy" Morrison, who played Scruno in previous movies in the series, is missing in action as well, although a character named Scruno, a racetrack worker, is introduced to the boys at one point and it's clear that he's new to them. He's played by another black actor, John H. Allen, who played the role just this once. The character of Gaby is listed as Gaby Dell in the cast list at the beginning, yet a newspaper headline about the character appears in the film and identifies him as Gaby O'Neill. Perhaps Gabe Dell, a series regular, was set to play the part, which is similar to the characters he generally played in the series, but pulled out at the last minute for some reason. The actor playing Gaby is listed in the cast list as Bernerd Thomas, a misspelling of Bernard. The other East Side Kids are played by a rather nondescript bunch, without much effort to differentiate them. Leo's father, Bernard Gorcey, turns up in a bit part as the driver of the horse truck sent by the glue factory. The elder Gorcey would, of course, become an important series regular in the Bowery Boys films, playing soda shop owner Louie Dumbrowsky.