Remember when movies needed to have a twist to get a spoiler tag?

Planet of the Apes: It's Earth.
Empire Strikes Back: Vader is Luke's old man.
Return of the Jedi: Leia is Luke's sister.
Dead of Night: The whole thing is a never ending dream.
Vertigo: The 'suicide' was faked.

Those films (and many more) become different films upon subsequent viewings, as the information contained alters the context of what came before.