Hank Azaria played the character of Danny Stevens mimicking Sheldon Leonard's voice, clearly as a tribute. Sheldon Leonard, who typically played gangster types during his acting career, became a well known producer of 60s TV comedies including The Danny Thomas Show, The Andy Griffith Show and the Dick Van Dyke Show.
Danny asks Midge "Do you know Loretta Young?", to which she jokingly replies "Only from temple."
Actually, Loretta Young was well known as a devout Catholic, and is buried at Holy Cross cemetery in Culver City.
About 19:25 into the episode there's an establishing shot of Rockefeller Center with all the state flags. The modern day Georgia state flag is shown on the left end of the screen, which was adopted in 2004, 43 years after this episode takes place.
When Abe tells Joel about the genius of the Weissman male child, Abe pours from a dimpled, three-sided bottle of Pinch Scotch.