Other mistake: They make it clear to us that the portals are one-way gates (from origination to destination). However, the last portal is two-way.
The Dark Tower (2017)
1 other mistake
Directed by: Nikolaj Arcel
Starring: Matthew McConaughey, Idris Elba, Jackie Earle Haley, Katheryn Winnick
Continuity mistake: When the Gunslinger rescues Jake in the forest, he fires far more shots than we see his gun is capable of holding when he reloads it.
Man in Black: Everyone who walks with you dies.
Roland Deschain: No more.
Trivia: At the scene where Jake and Roland are walking through the rusty theme park in Midworld, there is a huge sign saying "PENNYWISE", the name of the demon clown from "It", also by Stephen King.
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