Revealing mistake: When Ayla is looking at her "ugly" reflection in the lake she moves her hand down and a second later the reflection moves its hand down.
Revealing mistake: When Ayla gets her leg cut by the lion, the claw that cuts her doesn't look like a lion's paw (it looks like a bear) and you can see the "blood" is already on the paw and coming out of it as it dragged across her legs.
Answer: Completely made up. It was too difficult to teach all the actors ASL.