Ugh, that sucks but it happens to all of us. I find it is helpful to drink a lot of water the day after that kind of mistake. I don't know if it physically helps to flush out the calories, but it absolutely helps me feel more mentally on track. I figure that water allows my metabolism to work its best. Usually, by the end of the week, one bad night is only a small portion of the calories you consume and isn't the big deal that it felt like. The real sabotage comes when you let one bad night be an excuse for an entire bad day/week/month.
Oh, and next time you might be better off with veggie trays, fruit dishes, mini turkey sub sandwiches, baked chips, pretzels etc. No one will be sad if they don't gain weight at your party too