An early establishing shot ostensibly showing New York in the 70s shows the downtown skyline before the World Trade Center was built. Since the WTC began construction in 1966, it should be in any shot of that area from the 70s.
A cutaway shot shows a close-up of a stack of $20 bills. However, they are the new $20 bills, with the larger picture of Andrew Jackson and the bands of color, which came into circulation in 2003. As Action Park closed in 1996, these wouldn't have been used during the time period being discussed.