Objective: To determine if an audible movie soundtrack has a degrading effect on the auditory P1, N1, P2, N2, or mismatch negativity (MMN) event-related potentials (ERPs) in children, adolescents, or adults. Methods: The auditory ERPs of 36 children, 32 young adolescents, 19 older adolescents, and 10 adults were measured while they watched a movie in two conditions: with an audible soundtrack and with a silent soundtrack. Results: In children and adolescents, the audible movie soundtrack had a significant impact on amplitude, latency or split-half reliability of the N1, P2, N2, and MMN ERPs. The audible soundtrack had minimal impact on the auditory ERPs of adults. Conclusions: These findings challenge previous claims that an audible soundtrack does not degrade the auditory ERPs of children. Further, the reliability of the MMN is poorer than P1, N1, P2, and N2 peaks in both sound-off and sound-on conditions. Significance: Researchers should be cautious about using an audible movie soundtrack when measuring auditory ERPs in younger listeners.