Jonah manages to get a bottle of water to Gilbert, who is still stuck in the trash barrel. Gilbert takes a good swig of water. But when he rests his arm after the drink the bottle is still full and looks as if a guy Gilbert's size and state never touched the water.
They decide the car won't start because the battery is dead, because they left the lights on all night; but the engine can be heard cranking vigorously as they try to start it, rather than just sitting there inert as a dead battery would cause.
They make a big effort to get the trunk open, but they show the car remote on the key ring, which would have a trunk open button. However, the button would not work if the battery on the car were actually dead.
When Beach Patrol Alex is sinking in the sand, there is a large black gap between his feet. This is either the empty hole for the actor to sink into, or a glitch where the green screen didn't render the shifting sand correctly.
The boom mic is clearly visible in the reflection of the Lifeguard Tower window.
At no time do any of the characters appear to need to relieve themselves and the men always appear freshly shaven.