Well if you worry and obsess about it, I'm pretty sure it will undo everything.
BTW, that was sarcasm. ie, you can't do anything about it now, so you might as well just move on with your life. If everyone laughed and you otherwise seemed like a cool person that people wouldn't mind working with, it's unlikely that they would go out of their way to say anything bad about you. In fact, having been at several of those casual resident settings, I never felt moved enough to say anything at all really about a resident positively or negatively. When they say it's a casual informal setting, they actually mean it.