Walked out of the theater

I went to see this back when it was in the theater and ended up walking out about 30 minutes in. I had never walked out on a movie before at that point, probably because I would hate to spend the money for a ticket and not finish the movie. I actually got into this movie for free because my sister worked at the theater, so that may have helped. I walked out at the point where the dog stands on his hind legs and lets out this like squeal/bark sound that was like a code to the other alien dogs - does that sound about right? Was it like this alien dog came to conquer Earth and the sleeper agents they had already sent got too comfortable? Anyway, just thought of that for some reason.