I just heard about this from a friend:
Minor spoilers, but in the RS arc, Ruby gets attacked by a Salamance when he is a young kid.
Looks like the owner of that Salamance appears in the ORAS arc
When I first heard this, I was mindblown. Seriously. Like, how they managed to add the extra ORAS plot on top of the RS arc that continues on just fine - while giving additional details to the previous arc.