I think you were wrong. It's hard to expect a 2.5 year old to behave in a movie theatre.
I agree with others, just because the movie is during the day, doesn't give your children permission to ruin it for others. Constant talking is annoying during any movie.
The part that gets me about your post is that you asked the other parents what they expected you to do? Is it not understood that parents controll their own children? And if they can't then they take them somewhere more appropriate? (maybe you just used it as a figure of speech?)
Please don't take this as nasty, I'm not intending it that way, but I've come across this alot lately. Someone asks a parent to controll/quiet their child, and the parent sometimes responds. "What do you want me to do? She won't listen/be quiet/sit still?"
Why is it anyone else's problem but the parent's?
I just re-read this post, and while I mean what I'm saying, I realize it sounds nasty/bashing. It is not intended to be that way. Just matter-of-fact. KWIM?