Trivia: For the film, a real radio tower was built, albeit significantly shorter. The film was shot on a tall mountain, to give the illusion that the tower was much taller. A blue screen was placed below it. The two main female characters did their own stunts.
Trivia: Profanity Warning: The original cut of the film contained over 30 uses of the word "fuck." When the film was picked up for theatrical distribution, the studio wanted to redub the film's profanity to make it PG-13. The studio had the actors redub their lines with less harsh language, and then used A.I.-based software (similar to "deepfakes") to digitally manipulate their mouths to match the new dialogue.
Answer: They don't have the backpack at that time?