Yeah. They have heating packs. Pretty useful. I only heated like, two MREs my entire career though. Instead, I tended to collect the heating packs for cold nights in the field. You had to be careful (adding water triggered the heating chemicals, and released nitrogen gas), but if you just added like, half the amount required for heating the meal, you could stuff one up under your flak between your skivvy shirt and your blouse. Helped keep me warm on many a cold night.

EDIT : Also, MCI threw me off, too. In today's Corps, MCI stands for Marine Corps Institute; they're big red books with accompanying tests that you can study to learn new skills, and send them in for promotion points. I did a shit load of them in my 5 years. They have ones on vehicles, some on tactics, weapon systems, nutrition... the Leading Marines MCI and the Personal Financial Management MCI were required for me to pick up Corporal, and they also have shit like Math for Marines, Spelling for Marines, and Grammar for Marines.

My favorites were the M-240B Machinegunner, Small Unit Tactics, and Warfighter Leadership ones. Those are pretty cool. Counter-Terrorism is nifty too.