It's a small detail, but when you start a new town, Rover mentions that he hasn't rode trains often since 2002... when AC:GC came out.
I'm still wondering if the tapedeck Timmy sells to Reese is another small nod back to AC:GC.
I;m not really sure but you will face Blanca in your first adventure at the train when your 3DS set up to April 1..
I really want to start a new game on April 1st just to see this tbh