The car Steve and Mary "steal" is a 1930 or '31 American Austin Model A, which was built in Butler, PA, cost $445.00 ($7,000 in 2015) and had an engine that produced all of 15 horsepower, but it weighed only 1,130 pounds and got 40 mpg with a top speed of 50 mph.
The $50 Mary and Steve spend to spontaneously buy the puppy at the dog show would be equal to $782 in 2015.
In August of 1931 entertainment columns reported that Robert Williams had been injured in fall, requiring the recasting of his role in the film; Matt Moore took his place.
Midway through the film the principals are driving down Broadway, past the RKO Mayfair Theatre, prominent in the background--which just happens to be showing a recent RKO film, A Woman of Experience (1931), amidst an array of neon grandeur.
The ocean liner seen at the beginning of the film is the S.S. Leviathan. Built in 1914 in Germany, she was seized by the U.S. in 1917 when that country entered WWI. It served as a troopship during the war, with Humphrey Bogart among the crew. After the war is was acquired by the United States Lines, was completely refitted and resumed transatlantic passenger service in 1923. Never profitable due to Prohibition which made her a "dry" ship and the Great Depression, she was withdrawn for service in 1933 and finally sold for scrap in 1938.