You didn't miss too awful much; mostly stuff that's totally elementary to everyone here. Also, some mis-information as well, such as having a segment on THEL - Tactical High Energy Laser, which is chemical laser project that was cancelled in its current form years ago. I guess no one told the folks who put this episode together! They had old footage of it shooting down a rocket (which if you look up "THEL" on youtube you should easily be able to find plenty of footage of those tests).
Also, they had the Airborne Laser - the ABL, just a brief mention of that. Also the NIF at LLNL - currently the world's most powerful laser, when it is brought online in 2010. There's posts about that in the "lasers and science" section here. One guy demonstrated a 10W greenie - but it wasn't too dramatic as all he did was briefly stick a piece of paper in the beam - almost no fire and only some smoke! As we all know, you can do far more than burn paper with 10 watts! That was pretty pedestrian...
They had some other stuff, like microwave weapons and electrical discharge non-lethal weapons for stopping vehicles and such. There were some more melodramatic mis-information "facts" and a few interesting tid-bits. If you missed it I'm sure it will be on again sometime soon. That's one good thing about History, Discovery, AP, etc - they always re-run stuff quite often.
However, at least I'd give them credit for doing a show that spotlights lasers, despite the fact that there were some omissions and it was dumbed down a bit for non-laser people. After all, the laser has to be the most under-rated invention ever, you have shows about the invention and development of every other major modern day device, but precious little about lasers. Heck, there was even a whole show on the invention of flashlights on the History channel a couple years back (I didn't watch it but saw it listed in the guide) - why not a whole show on lasers!?!?