Towards the end of TNG: Future Imperfect, Commander Riker realizes that the "future" Enterprise that he's been a part of is actually a fiction. He sees this for certain when his wife in that reality is a holodeck character he encountered in the real world.
Upon going to the bridge and after speaking to Geordi, he then talks to Worf, asking him where he received his wound, what battle, etc. Worf only is able to say that it occurred "in combat". He then speaks to Data who uses a contraction, which Riker points out to be an absurdity.
After "Tomalak" reveals the deception, Riker tells him that one of the things that opened his eyes to the fiction was the computer lag. I suppose that the "computer lag" can be understood to be a lack of processing power for the alien Barash's "holodeck." Is this why Data spoke with a contraction and Worf (apparently) did not know the answers to Riker's questions? Or perhaps was it something else?
(And yes, I understand that Data does speak contractions from time to time prior to this episode. However, since Riker called him out on it, either Data purposely goes out of his way to try to not use contractions, or any time he does so it's a glitch within his system, and Riker somehow knows about it.)