Forgot to put middle name on plane ticket? is it still ok?

I've been to Thailand several times and have never had my middle name on my ticket even though it's on my pport, and I've never had any problems. "Depending on customs at the airport" pretty much means you might get a customs officer looking to supplement his income - you can pay your way out. They'll make up some story about how it's a problem but for a certain amount they can fix it. You can either tell them "no problem I'd like a receipt thanks" and they'll let you go without paying the bribe. Or if you don't want to risk the hle, just pay up. The good news is they're not that greedy, they'll probably ask for the equivalent of $10 (or at least that was the going rate to get out of a traffic fine last time I was there). You'll be fine.