In the 1942 original movie, Thumper had five sisters. Here, he only has four.
As Ronno is talking to Bambi and Faline for the first time, the notch on his ear vanishes every once in a while, then it returns.
After Flower said "See? I told you turtles were scary!" When Bambi laughs, the rest of his forehead is suddenly colored in when it's not supposed to be.
In the original 1942 film Ronno had brown eyes as a stag while in this film he has green eyes as a fawn.
In the 1942 original movie, Bambi's mom said, no deer lived half as long as The Great Prince of the Forest. In other words he was more than twice as old as any deer she knew lived long enough to be. That would make The Great Prince much older than she was. In Bambi II, however, The Great Prince told Bambi (still a young fawn) that he was Bambi's age when he met Bambi's mom for the first time. Although, she may have been exaggerating.