Berger began as an assistant editor on the 1973 film Arnold, in which Star Trek: The Motion Picture actor Norman Stuart played the title role. The score for this film was composed by George Duning. Berger next edited George C. Scott's 1974 adventure film The Savage Is Loose, which marked Berger's first collaboration with fellow film editor Michael Kahn. Berger then worked as one of Kahn's assistant editors on the 1975 horror film The Devil's Rain, which starred William Shatner.