Avengers: Age Of Ultron - 32 Easter Eggs, In-Jokes And References
5. Caps Shield Bike
When Black Widow's motorbike is unveiled in the sequence featuring the Vision heist, she retrieves Cap's shield from the motorway after Ultron knocks it away.
After a typical quip about clearing up after the boys, she puts the shield on the front of her motorcycle, which is obviously a homage to the late 70s Reb Brown Captain America films. They had Cap riding his own bike with a round windshield that was a direct homage to the shield.
The addition of Cap's electromagnetic gauntlet is also a reference to earlier iterations - this time the 1960s Avengers comics.