As with most myths, three is a very common number in CT. Three mystic knights, Three party members at a time, Three gurus, Three in the Zeal family, Go around the room Three times, Find Piette in the lineup of Three identical knights. Six explorable destinations in time (not counting 1999AD) with Three in the past, and Three in the Future (compared to the beginning of the game). Six robots beat up Robo (Three each in two rows.) Need I go on? There were three Gates when you first showed up at the End of Time. You "collect" six more. Most bosses are a max of three things to hit, sometimes one, but rarely two, and never four or more.
Not really trivia, but definitely a tidbit.