The "beer" from the fridge in the garage was actually carrot juice. It was the only period-appropriate can the production crew could find, one lacking any pull-tab that meant Don had to open his beers with the sharp end of a can and bottle opener hanging from a string by the door.
Elvis' return from Germany is mentioned in this episode. Elvis Presley was drafted into the Army in January 1958, but it was deferred until March 1958. This enabled Elvis to star in the film, "King Creole." He left for overseas service in Germany in October 1958, and returned to the US in March 1960.
In the opening scene, Don is sitting in a train looking at a magazine ad with a bemused expression. It is the same Volkswagen "Lemon" ad he later sees in Danny Siegel's portfolio in Waldorf Stories (2010).