The position of the box spring on the edge of the pool changes position continuously.
The rock that hits Dee falls to the ground, yet the next scene shows her picking it up off her chaise lounge.
When Dee snots at Casey the pool attendant in disgust at being rejected from the club pool, if you look carefully, you can see boogers actually hanging on the left side of her upper lip, which disappear immediately as they cut shot to switch to the pool manager's reaction and back.
When Dennis is tackled and the table collapses, the sound of breaking glass is heard. Is it doubtful that a club would allow glass in their pool area.
When Mac and Charlie are throwing rocks at each other at the bottom of the pool they found, one of the rock hits Mac in the hand where he is heard saying" that one hurt, that really hurt...that really hurt." However, Mac's face is visible at this moment and his mouth is not moving but rather baring gritted teeth.