... the old hex cookers gave off cyanide when burnt.
At least they printed a warning on the back of Claymore mines:
WARNING: EXPLOSIVE IS POISONOUS IF EATEN
DO NOT BURN - PRODUCES TOXIC GASES
Of course, no mention about the main hazard of a Claymore mine, although they helpfully printed on the other side:
FRONT
TOWARD ENEMY
An essential item to add to a survival kit is a roll of duct/gaffer/gorilla tape and a Leatherman multi-tool or equivalent - don't buy cheap knock-offs.