Interestingly enough, I found the Developer Room quite by accident. I had no idea there were multiple endings (first playthrough I rescued Crono, recruited Magus, and destroyed the Epoch so that Crono's mom chased the cats into the Millennial Fair gate), and I was doing my first NG+.
I went to the Ocean Palace and remembered that I was supposed to lose... but decided to see what happens if I didn't. So I gave it my all and...
...discovered the Developer's Room.
Suffice to say, I was devastated by the one gag in which the guy says something along the lines of "want to see a screenshot of Chrono Trigger 2? ... Yeah, that'd be nice!" I was seriously heartbroken. My eleven or twelve year old mind was quite saddened by that joke, as I was wishing for a sequel already.