 In December 2017, Collett's casting in the adventure comedy film "Dolittle" was announced.Released in January 2020, the film features the actor starring as Tommy Stubbins, the self-appointed apprentice of Dr. Dolittle (Robert Downey Jr.).Collett has also had a stage career, appearing in productions of "Billy Elliot the Musical", "Matilda the Musical", and "Elf, The Musical".