The paintings in the Devil's throne room depict him in his various transformation during the battle with him in the video game. As a spider, a goat and a snake like creatures.
It's revealed that Cuphead's favorite song is 'The Daring Young Man' on the Flying Trapeze.
The character of King Dice, including his singing and dancing ability, is very obviously based on Cab Calloway, the most popular singer of the 1930s and a frequent guest for 1930s cartoons on which this series is based.