The logo of Dean's "Rocky's Bar" is written in the same font and colors as the "Rocky and Bullwinkle Show" logo. This is a nod to Crowley's old nickname of "Squirrel" (as in "Rocky the Flying Squirrel") for Dean. Sam's nickname was "Moose" (as in "Bullwinkle"). There is also a mounted moose head in the bar, and a squirrel holding a beer in the counter.
Baby's original Kansas license plate (KAZ 2Y5) from seasons 1 & 2 is hanging up behind the bar next to the "Rocky's Bar" sign.
In the opening sequence, "Daphne loves Fred" is carved into the bar. This is a direct reference to ScoobyNatural (2018) where Sam, Dean, and Castiel get turned into cartoon characters and join the gang of Scooby Doo, Where Are You! (1969).
The monkey statue sitting behind the bar by the "Rocky's" sign was from Ellen Harvelle's road house in Season 2.
All the beers on tap in Rocky's are available in Family Business Beer Company, a real brewery Jensen Ackles is part-owner of.