Entirely wild-ass guesses here : Roger found some way to play with gravity, force fields, and ultimately time (or Portal tech ?).
a) he has a cool trench coat : he NEVER wore any before
b) he sports some tech stuff on his wrists
c) he bounces on the floor, then the wall without really touching them, 'cause we see some cool blue electric arc thingie of rebound
d) his entrance is the consequence of his tinkering with whatever he was tinkering with (wormhole gun ?), which we were warned about with the 3 lasers we saw in the background when Doc was having his date at Cara's : 1st laser beam is the discovery of the effect, the second one sends our good ol' racoon to wherever he came back from (the future or an alternate timeline entirely populated of Sports illustrated cover ladies, yay) with the help of the third beam, through the office window.