Things you didn't notice before in Mario games

It's because CPUs operate in mysterious ways and use clever strategies and rituals to appease the RNG gods. Next time he gets lucky, you will get the answer.
 
There are two different credits themes in Mario Kart DS.

One is for 50cc and 100cc. The other one is for 150cc and Mirror Mode.

150cc and Mirror Mode has the longer one. Audio differences are subtle, but if you listen hard enough, you can hear them.
 
The first one is slower paced in the latter part, the second one is faster-paced instead.
 
In Brawl (as far as I know, this could apply to other games), DK's head will sometimes clip into his chest whenever he climbs up a ledge quickly
 
I remember always dreaming of a multiplayer M&L game ever since my first moments playing through Dream Team. What I didn't know was that there already is a multiplayer M&L game: Superstar Saga. At least, it kinda sorta is when played on a GameCube or a Wii U.

Connecting two controllers to either system when playing GBA games will register them both as P1. Not sure whether this was actually intended by the devs, but in Superstar Saga, this essentially creates a multiplayer experience as long as one person uses specifically the A Button and the other uses specifically the B Button.

Various walkthroughs utilizing this have been posted on YouTube, and soon I want to try playing the game with my brother to see how well it works. I imagine Bros. Attacks will require a lot more skill and coordination then previously, especially considering that my brother has not played the game before. But whatever the case, I think it's really cool that the option for multiplayer was there from the very start of the series, even if it might not have been intended by the developers.