Asklemmy

The biggest, most monstrous dildo you can find.

He never uses it. Just befriends it and talks to it like in the original. Just leave the possibility hanging there.

A tennis ball.

Magic 8-Ball

This time Wilson can kinda sorta actually talk back.

couch cushion

An MRE. When supplies dwindle, our protagonist is faced with a tragic choice.

The severed head of a man named Wilson.

A coconut. Those who know, will know. Those who don't, may their innocence last forever.

Coconut would be believably available on the island, and you could have a whole arc when he runs out of water and fights over killing his friend to drink the juice, like a schizophrenic episode

Oh wow look at what the tides have swept ashore. A Pringles can, some rubber gloves and a few sponges.

a super valuable in-the-original packaging giant boba fett action figure, he's tormented by keeping it mint in case he ever gets back, somehow the rocket launcher ends up saving his life.

A bowling ball. Can change some of the script so he catches it before it rolls off the raft but he falls in the water with it. He's too heavy and weak to make it back to the raft so he has to let go and watch it immediately sink or he's taken under too (also a good reference how it's hard to save someone from drowning when you're near drowning yourself). Definitely thought of a dildo first till I saw everyone else put it up though.

A pot plant which he might try take care of for a while before realising it's plastic, but has already grown attached to it.

A dakimakura, AKA a body pillow. Needs an anime character on it, obviously.

Wouldn't the object need to be something of deep importance to the individual or be a poetic representation? I always assumed the volleyball was a symbol of everything he left behind. Things like recreation no longer mattered; only survival. :shrug: but I also thought the movie sounded incredibly boring. If you want a random item, go for qualities like "awkward to carry" or "gets hot when left in the sun". Give your characters personality or force them to choose that object at a moment it's inconvenient.

• An oversized diamond/ faberge egg - it's valuable, heavy or fragile and inconvenient, in a critical moment your character may need to smash it against something risking damage
• Teddy Roxbury/furby - favorite toy growing up? Creepy voice at stalking moments? Mid point twist when the batteries die?
• Harmonica - potentially a little Disney princess forest friend vibes
• Bowling ball - Wilson prolly plays a little different when it's not feasible to take him on a raft, prevents you from climbing trees and burns precious calories transporting. Mobility is now a plot point. Decent weapon tho
• Toilet plunger/brush - everyday object that can be utilized differently, maybe adds that little bit extra reach to save the day?

A 1ft tungston cube

A fleshlight.

Couch

A dildo.

Wilson from House M.D., who, after surviving cancer, decided to retire from oncology and live as a recluse on a desert island.

Can I just suggest that to mix things up a bit, this one should be set on a peninsula.

Miss Piggy.

A walkie talkie that he can't find any batteries for.

Do your work for you, you say?

Or is this a hobby project?

A furby or tickle me Elmo.

The corpse of Harry Potter that's slowly coming back to life

Oh wait, that movie exists already

A toaster. Toasters are friends

The same volleyball, but he's imagining it and he's the only one who can see it.

A mannequin