Dame Elizabeth Taylor replaced Maria Flynn in the role of Priscilla. Some sources say Flynn was afraid of the dog on the set; others say that she grew taller than Roddy McDowall or that the strong Technicolor lighting caused her eyes to water. In any case, production was halted. Producer Samuel Marx was walking the 600 block of North Foothill Road in Beverly Hills doing his nightly patrol as an air raid warden when he met Francis Taylor, who patrolled the 700 block. Knowing he and Sara Taylor wanted to get their daughter into the movies, he asked him to bring Elizabeth to the studio. There she was introduced to Lassie and the production resumed.
Pal, who played Lassie, earned a salary of $250 per week, while young Elizabeth Taylor was paid $100 per week.
Though Lassie is supposed to be female, this and all subsequent Lassie movies used male dogs to play her, supposedly because males are easier to train.
After a nationwide hunt for a suitable dog for this movie failed, MGM called in dog trainer Rudd Weatherwax. He had many purebred collies, but Pal, his one-year-old male collie (who had no papers), easily won the role. Pal retired at the age of five, after which, nearly all subsequent Lassie movies used his direct descendants. [The dogs who played Lassie for the first half of season 2 of Lassie (1997) and Lassie (2005) were not.]
The number of purebred collies registered in the United States in the late 1940s increased from 3,000 to 18,400, probably because of the Lassie film franchise.