Continuity mistake: Right near the end of the film, one of the characters is driving away from the caves and eventually pulls over onto a grass verge where she breaks down in tears. Seconds later, a lorry carrying logs drives past her sounding the horn. At this point, you can see that her vehicle is now on the road.
Revealing mistake: Towards the end when Sarah and Juno team up to find the exit, they pass underneath some thin stalactites. As Sarah goes under them, one of them wobbles as if it is made of rubber. In reality stalactites are rigid formations and are not supposed to wobble when touched.