I was fiddling around with movie Megatron the other day and figured out how to combine the two arms like the instructions say (but don't show how to).  However, I couldn't figure out how to get the fusion cannon part of his left arm to stay open due to the spring that snaps it back into place.  Another problem was that the claw hand which looks like it's supposed to launch doesn't, because it has no spring.  I figured I'd eventually get around to swapping the springs, but was still slightly baffled by the two-arms-into-one-cannon thing.  So, I asked around the TFW2005 Washington Sightings thread  (where I post often), and was directed to this thread.

Man, did that ever help clear my vestigial confusion and help motivate me to modify Megatron.  He went from a "Good" toy to a "Great" toy in about 10 minutes.  It would have happened sooner, but I dropped the spring and it took a couple minutes to find the dang thing.  Now, my Megatron can fully utilize his fusion cannon and bitch-slap Optimus Prime, though not at the same time mind you.  I do have to wonder if the factory intentionally constructed the toy this way or if there was some miscommunication somewhere.  It doesn't matter though, because mine is "fixed." Huzzah!