When Jack Kennedy is about to speak to the Gold Star Mothers of Charlestown, his campaign manage pins a medal on his lapel to impress the ladies. The medal is an Army Commendation Medal. Jack was a Naval Officer and therefore never awarded this particular award.
Both Joe and Jack are separately seen leaving home to go to war in a green Bentley Mk VI.
This model was not built until after the war. Later shots show Jack campaigning in 1946 in the same car. Shots show it is the long tailed model, the "R type" not introduced until 1952.