The blue cloth belt Cassidy Gifford wears on her jeans shorts is missing when she is outside the cave, 42 minutes into the movie.
While one girl is climbing up, the rope begins to swing. With the girl hanging in there with full weight, it is not possible for the rope to swing without the girl losing height, which only happens significantly later.
In the 29th minute they first see the advent of time passing quickly through an opening in the cave, allowing them to see the sky. But it is always light outside. Even if night represented only eight hours of each day, then one would see the skies passing in darkness one third of the time, hence there would not be constant daylight visible to the eye or entering the cave.
The natural light entering the cave where Cara, Jackie, Taylor and Veeves rappelled down should have rapidly alternated with the changing of day and night after they crossed the time warp threshold, just like it did for Dr. Hopper.
When the main characters use the 'magic' ladder you can clearly see welds in the metal which going by the insinuated technology shouldn't be there.