Doing it at the park was nice in some ways, because we didn't have to plan too much in the way of activities. We kept it simple and let them enjoy the playground.
And we did play just one game: Pin the Nose on Olaf.
A thematically appropriate gift from buddy Caroline:
I love this one, with all the little heads leaning in:
Ah, la piece de resistance! Instead of a birthday cake, we had Frozen Birthday Trifle, a decadent concoction consisting of jello, Cool Whip, and blue-and-white striped marshmallows.