One of the most memorable scenes in “Last Action Hero” takes place in a video store within Jack Slater’s fictional universe, where Danny discovers that in this world, Arnold Schwarzenegger didn’t star in “Terminator 2: Judgment Day.” In this world Sylvester Stallone played the Terminator.

That means that if a movie stars a particular actor, then any other movies that actor appeared in will have been recast within that corner of the multiverse. So if Lydia Tár goes to see “The Lord of the Rings,” she’ll find that the character of Galadriel will have been played by someone other than Cate Blanchett. 

This opens up a gigantic can of worms in the MCU, because the cast of the Marvel franchise is sprawling and the characters keep bringing up various real-life movies, so we know those films exist in their world. That means that when Tony Stark refers to Thor as “Lebowski” in “Avengers: Endgame,” the “Big Lebowski” movie Tony Stark watched couldn’t have starred Jeff Bridges, because Jeff Bridges played the villain in the first “Iron Man” movie.

It gets worse: Spider-Man brought up the “Star Wars” movies in “Captain America: Civil War,” so that means that Harrison Ford — who has been cast in the next “Captain America” movie, didn’t play Han Solo in the MCU. (Maybe it was Glyn Turman, who in real life lost the role of Han Solo because he was black, Carrie Fisher was white, and their romance might have caused “too much controversy.” Sigh.) 

While we’re at it, Oscar Isaac (Moon Knight) didn’t play Poe Dameron, Andy Serkis (Ulysses Klaw) didn’t play Snoke, and Samuel L. Jackson (Nick Fury) didn’t play Mace Windu. That “Star Wars” list just goes on and on.