I know there's a lot of inconsistency, plenty of "plot holes" and tons of plain old head scratchers in the overall story of TF2, but this one particular moment jumped out at me on first viewing. It, to me, really exemplifies either lazy writing or lazy execution of the writing... or something. After fighting tooth and nail with Optimus, in order to get to Sam, AND finally defeating him, Megatron... well, he... he. just. leaves. Whuuu? Understandably, after the fight he just put up (undoubtedly a little drained) he may not have wanted to contend with the arriving Autobot forces, but besides trying to kill Optimus, what he was doing was TRYING TO GET SAM! THAT'S WHAT HE WAS DOING! So in a nutshell, Megatron kills Optimus with no other Autobots around. No one else around, except Sam. Optimus crashes to the ground, immobilized, while Sam stands helplessly nearby and Megatron, with nothing to stand in his way of grabbing the boy, bolts. Wow.