On the flight out of Superfundville (in itself a joyous occasion), I was sardined back in coach (the attorneys upgraded to First Class). Apparently opposing counsel's attorneys didn't have the same budget, because they were a row behind me. (I suspect they made their paralegal hitchhike home.)
They spent the first 20-30 minutes talking about the case, and I did my best to ignore it. Obviously they didn't see me, or more likely recognize me. When they began getting into more critical and potentially sensitive stuff, I simply pulled out my business cards, reached over the back of the seat and dropped one in each lap. The conversation quickly stopped, although they didn't say anything to me. At least I got to spend the rest of the flight in relative quiet.
Moral of the story - don't discuss confidential information during travel. You might be on the same plane/train with opposing counsel or their staff.