Thunder / Dylan (voice)
Maggie (voice)
Jack / Carlo (voice)
Mr. Lawrence (voice)
Daniel (voice)
Chihuahua (voice)
Carla (voice)
Nurse Baxter (voice)
Izzy (voice)
Mark Matthews (voice)
Mike Matthews (voice)
Hospital children (voice)
Reggie (voice)
Audrey (voice)
Lasondra (voice)
Mr. Eames (voice)
Mrs. Eames (voice)
Old Lady (voice)
Cat sounds (archive footage; uncredited)