As an actor, you have to keep secrets.
Sometimes you have to keep your casting under wraps. Or the story line. Or the nature of your contracts. There are so many things that actors have to keep secret. Many times, not doing so can result in legal action against you. Or you have a situation that casting director Lana Veenker recently blogged about. You may recall a young extra revealing the results of the prom court on Glee by tweeting from set. There was a huge backlash and she may have a hard time getting hired again.
If you are not sure if you can share a piece of information, ask! Ask the producer, director, casting director, your agent, whomever is your best contact about it. It is always better to say too little than too much.
I have a lot of secrets I have to keep. Some I will never tell, some…. well you will just have to wait and see 😉