I think what that poster was trying to say was that the end of Disney films are not always the memories and images we take away from them. Ariel throughout the parks is usually depicted as a mermaid, even though she changes into a human at the end of the film. Pinocchio as a puppet, and not a real boy. The list can go on and on.
The point was, you had disagreed with another post and said getting Rapunzel's hair wrong was "a big oops", even though the common image of Rapunzel is with long blonde hair. These types of "errors" in Disney parks compare to the portrayal of characters from films such as Beauty and the Beast, The Little Mermaid, etc, where the portrayals of characters at the end of the films do not necessarily correlate with the park's portrayal of the characters.
This isn't an error, or a big oops. It just makes much more sense when The Little Mermaid is portrayed as a mermaid, the Beast is the Beast, and so on.