In addition to my "add an option to lock the screen on lens close/application close" idea.
I wish to propose another from experience

An option so when the torch timer expires it flashes a light (red or white) or maybe even beeps every 3 seconds or so.

I went up into a customers dark loft space today with my Lanterne and propped it up against a wall so I could see. I left the loft space to check something but upon my return the light timer had expired and the device was "missing".

15 minutes later (after borrowing a nearby If-fone of all things) found that the clever N900 had managed to slide down the roof joist, bounce off some cabling and roll itself up in some loft insulation. It seems the vibration from someone digging the pavement up outside had disturbed it.

A "Lanterne Standby Light" may have helped locate and not forgot the location of your device.