When aliens come to earth in movies, they always seem to have just one way of speaking.
We've got so many. English, other ones, animal sounds...
Of course, the alien astronauts are probably from a specific class/location/etc., or they've agreed to use only one language on their mission for sake of efficiency, so maybe it's wrong to assume that their planet doesn't have as much diverse culture as we do.
Okay, never mind! Carry on! And on. And on.