When Rusty is at the river rescuing his sister from the alligator, the alligator which lunges at Rusty is clearly a fake.
When Rusty's friend, Rebel,takes Rusty's little sister on the skateboard, the puppy's head is sticking out of the backpack. In the first shot the puppy is clearly a stuffed animal not a puppy.
Shortly after Rusty rescues his little sister from the alligator, the pigeon, Coo, tells him to head for the "dry mountains." There no mountains along the Gulf Coast where there might be alligators.