Jeremy loses his swimsuit and Mac holds a towel up for Jeremy who wraps himself in it (from 14:39 to 14:43). Then there's a shot of Mac swimming underwater (from 14:44 to 14:48). In the very next shot (from 14:48 to 14:51) Mac's running alongside the pool with Jeremy who is still wrapped in the towel.
Mac does his trendy dance routine by the poolside (from 14:52 to 15:05). The crowd of kids is not the same in each shot.
Felix leaves the cell phone in the shade (at around 30 mins). But when Chase picks it up (at around 34 mins) it's in a different position and in bright sunshine.
At the end of the film, Chase jumps into the pool feet first (at around 1h 18 mins), but in the subsequent underwater shot Chase is shown diving in head first (at around 1h 18 mins).
When his mom goes into Chase's bedroom to answer the cell phone (at around 23 mins), the notebook is at the foot of the bed rather than a foot from the footboard as it was (at around 22 mins) when Chase went into the bathroom. When Chase emerges from the bathroom and returns to his bedroom (at around 30 mins), the notebook is still at the foot of the bed, but the bedding is an inch or two lower than it was before, clearly exposing the top crossbar of the footboard that had been out of sight before.
Chase takes the battery off the cell phone when he's talking to Mac (at around 1h 01 mins), yet he continues the call. The line is broken when you take the battery off.
After Jeremy loses his swimsuit, and is meant to be naked, he's clearly wearing a dark-colored swimsuit (at 14:24 and 14:32).