In 1991, David Ogden Stiers made a guest appearance on "Half A Life", a season 4 episode of Star Trek: The Next Generation. I watched TNG when it originally aired, and I remembered being delighted to see Maj. Winchester again!
What I didn't know was that there was an Easter egg buried in the show, as a nod to Mr. Stiers' former TV gig. Look closely on one of the control panels in Engineering, and you'll see a familiar set of numbers:
I never knew about this gag until it was mentioned on the great Mission Log podcast, an episode-by-episode look at Star Trek in all its forms. Nice job, ST: TNG art department!