Andre was a harbor seal, and was portrayed in the movie by a sea lion. The father trained him even though he had no experience as an animal trainer and found Andre to be very intelligent and easy to train.
Shots from original 16mm films of the real Andre appear during the credits.
A sea lion plays Andre. Seals are notoriously difficult to train.
Paula suggests naming the baby seal "Marky", after her boyfriend. In real life, Harry Goodridge had found a seal pup a couple of years prior to Andre, and named it Marky. Unfortunately, Marky didn't survive.
Jay Brazeau and Shane Thomas Meier have co-starred together in voice roles on Bucky O'Hare and the Toad Wars! (1991), G.I. Joe (1990) and Adventures of Sonic the Hedgehog (1993) as well as both having appeared in Mom P.I. (1990), MacGyver (1985) and 21 Jump Street (1987)