Really, very nice work. Just for fun, here's the 40s/50s-style noir version, which works as well if not better.
I like how, in the 1st and 3rd panels, the background characters are on the right and, in the 2nd and 4th panels, they're on the left. Balances things out.
Also, in the 1st and 3rd panels, the character in front looks directly at the viewer while, in the 2nd and 4th, they look away to the left.
Both Gosling's and Penn's characters appear first wearing a hat, then not.
The only deviation (really, for this banner, it's an error) is the position of Gosling's head just below the top of frame, whereas everyone else has the top of the head cut off. Another inconsistency is the placement of the background characters in the 1st and 3rd panels -- Gosling is closer to center and his left shoulder is in frame while Penn is closer to the edge and his left shoulder is cut off. Background characters in the 2nd and 4th panel have matching placement.
However, all things considered, nicely thought out.