Dave has a pet snake as a guardian against assassination.
Charlotte tries to hide a venomous snake in Dave's hotel room, but it bites her instead.
Charlotte hides a venomous snake in Dave's room so Dave won't see her coming when she attacks him
Double Subverted: ...but when she drops it and runs to find a doctor, it hides on its own, and later bites Dave anyway.
Every time Dave steps into his hotel room, he staggers out again shortly afterwards, having been comically savaged by some new spider, scorpion, snake, or jellyfish that was hidden in there.
The snake is dressed up like a hitman.
Zig Zagged: Charlotte is accidentally bitten trying to hide a snake in Dave's hotel room... and Dave is the only doctor on the island, forcing her to confess to him... needlessly, since he doesn't actually know anything about that particular kind of medicine... causing Charlotte to loose her temper, pick up the snake, and start beating him with it... until a passing herpetologist casually informs them that the snake isn't actually a poisonous variety in the first place... at which point Charlotte and Dave resolve what turns out to have been their lovers' quarrel. (And in a little snippet after the credits, we see Charlotte getting fined for cruelty to animals, the snake having finally escaped to call the cops on them.)
Invoked: Charlotte specifically decides to use a venomous snake after seeing it in a movie.
Exploited: "Psst. Wanna buy a dangerous animal? I got snakes, scorpions, spiders... the works. Sure, they're expensive... but I don't ask questions, ya get me?"
Defied: Dave has his room thoroughly checked before he goes into it, and makes certain there isn't any way for something to be slipped in while he's asleep.
Discussed: "What, you think this snake got in here by accident? Haven't you ever seen a James Bond film?"
Conversed: "Why do movie assassins always use animals? They're so unreliable."
Deconstructed: Charlotte is shown having so much trouble acquiring, looking after, and delivering the snake that she realises what a waste of time it all is.
Reconstructed: But the snake ends up in Daves hotel room anyway, bites him, and the death is dismissed as an accident. The expenses Charlotte incurred finding and carring for the snake are more than offset by her payment for the job.