Deliberate mistake: Coming back to Earth in 1998, Stone is amazed to see the Cincinnati Reds and the NY Yankees on TV in an interleague game. This wasn't yet possible in '98, as an American League East team could then play only a National League East team (and the Reds are NL Central). But the producers put it in anyway as their own little "fantasy baseball game," because these were their favorite teams.
Winning Through Intimidation - S1-E15
Deliberate mistake: In the actual card game, attacking the castle ring would not be allowed, but this is probably done in order to enhance the show for kids.