I've looked at this box several times. The clip is rather loose, not in terms of how it's attached, but how tight it is to the body of the box.

Something for water purification.

Offload the duct tape to the outside of the case, by wrapping around it sidewise. This will also make it more secure.

I'd also find some tiny zipper bags and use it to carry those matches- that case isn't terrifically waterproof. (Try the crafts section.

I'd replace the headlamp with something a little smaller like a Photon or a Solitaire. I assume that is what the batteries are for? If so, I'd carry ONE (1) spare set of batteries, with that being a single battery, if rated battery life was under 12 hours. But that's just me. I'd also make sure that the batteries in there were brand new in both cases, and use something that can't be turned on accidentally.

Your mirror looks a little busted up. At the very least I would tape over the broken edge, if not replace it. A kit this small, you might even think about a mirror cut from a rearview repair kit. (Automotive section of Walmart.)