@tvaziri examines the theory of whether the switch of Twin Pines Mall to Lone Pine Mall in Back to the Future is an Easter egg or thing in the movie.
My definition of Easter Egg is a sly wink or nod for the audience to notice and feel a sense of satisfaction, while a thing in the movie is something that should be in the movie because it makes sense or is required for continuity.
I didn’t even catch the Lone Pine Mall change until after I rewatched the movie several hundred times, but, it makes sense and follows along with the plot of the movie. To me, it’s a thing in the movie. You’ll have to watch the video above to see what @tvaziri decided.