Revealing mistake: Becky calls Dan on her iPhone, as she puts it to her ear you can still see the contact info while Dan's voicemail is playing and not the actual call duration screen. (00:05:21)
Revealing mistake: At the end, when Becky is descending down the tower on the rope to where Hunter's body is, watch carefully in the far-off close-up, and you can see the bad CGI, as her feet aren't even touching the tower.






Answer: Most likely, that never occurred to them, or they had no idea about how to do that. Not to mention, it would be extremely dangerous, physically difficult, with no guarantee it would be successful.
raywest ★