This app was mentioned in 2 comments, with an average of 1.50 upvotes
Some kind of portable shelter. Tent, sleeping bag, etc.
At least one way to create fire.
A way to collect and store water, as well as a way to purify it (even if just boiling it in a pot).
Water resistant solar/crank radio and flashlight, that doubles as a USB charge pack.
Cellphone (waterproof and has a freaking amazing app* and maps** and first aid***)
Durable survival knife that can handle batoning.
Layers. Like, lots of clothing options.
Rope/twine.
Backpack to put all this stuff in.
AR-7 with a pile of ammo. Waterproof, floats, light, compact, good enough for hunting small animals (which is all you'd be eating without a way to preserve them), light ammo (.22)
*https://play.google.com/store/apps/details?id=tomplesko.app.esensor - Pretty brute interface, kind of looks like LCARS from Star Trek. Basically lets you access the raw information from your phone's sensors, like direction, GPS info (lat, long, elev), travel, etc.
**Google Maps lets you download map data to your phone, limited only by the space you have, so get an SD card.
***There's a number to choose from, so it's best to check them out now before you need them.
Of this list, the only thing I don't have is the gun.
This is probably the best sensor suite you can get for an Android phone that doesn't require any external devices.
https://play.google.com/store/apps/details?id=tomplesko.app.esensor