*This isn't legal advise, just experience*
Things being "right" and "legal" doesn't keep you from being sued.
I apologize for being misleading. I can’t find where I suggested
one cannot be sued but you clearly got that from my post. Anyone
can sue anyone for anything. That does not mean it is in any way
illegal or not right to have a character in a movie say the name of
a company like “facebook”.
Images and trademarks are not part of the question so I deliberately
didn’t mention either. The question was about mentioning “facebook”
and “twitter” in a movie. It is legal to mention both. It is legal to have
a character in a movie say “facebook” and/or “twitter”. That falls under
free speech.
Cyguns, what lesson did you learn the hard way? Were you sued by
a company because a character in one of your films said the name of
the company?