Vegeta and piccolo from dbz movie?

It was a gag, lol.

That wasn't the Broly movie, that was the Super Android 13 movie, the movie that came before the Broly movie. Anyway, it was a gag. It meant to say that the end of the movie would only come when the fish would jump out of the water. It's also a dub line, meaning it wasn't in the original Japanese version of the movie and thus not truly part of the movie. If I had to guess, the meaning behind it is the same as saying "It's not over til the fat lady sings". As the fish jumped, this signaled the movie was over. The people responsible for the dubbing probably didn't know on what line to end the movie so they probably thought "let's add a small gag using that fish". It's just a silly last joke instead of adding silence, a common practice in dubbing because for some reason American viewers, most likely kids, cannot appreciate the value of a silent moment.