I went for a walk last weekend, so I had my gear out cleaning the dust off the night before.. List of gear as follows...
Sony Handycam AX53
Garmin Virb 360 camera
Tascam DR05 sound recorder
EPIRB
Power bank
Snake bite kit (also useful for other injuries)
Knife
Torch
Laser pointer
Lighter
Paracord
Water filter
Obviously more gear can be added, but imo it helps travelling light, especially when off trail.
If I could add a few more things to that pic, I'd throw in a Survival blanket, Emergency poncho, Ziplock bags, Secateurs, a Silva compass and a local topo map..
If you use your phone for primary navigation which I do, be sure to have your map data pre downloaded and a charger. I use back country navigator, its free and it works well.. Ideally having a purpose built GPS is a wise choice, but until then this gear will suffice.
Above everything else, make sure you dress for the worst of conditions and check the weather forecast before you head off, stay safe..