Urban Legend of Zelda: There were false rumors of an on-foot graveyard level. Although, at one point, there are gravestones along the roadside.
What Could Have Been: The prototype for Spy Hunter originally played with the James Bond theme, which was the theme originally sought after for use in the game. The Peter Gunn theme was used when Midway could not obtain the rights to use the James Bond theme in the game.
A helicopter sequence was originally planned, but was deleted due to lack of time and memory. Although the later Super Spy Hunter game featured a flying car level and a jet plane sequence.
There was also going be a live action film with Dwayne Johnson in the starring role, but it appears to be trapped in Development Hell so far. However, a sample of it can be seen in the last game in the franchise, Nowhere to Run.
Speaking of James Bond, there's an homage to a famous stunt from Live and Let Die: after missing an exit from the river one will encounter a small island. On a properly set-up arcade machine, accelerating to top speed before reaching this island allows the player to jump his boat over the island rather than crashing as will happen when running into any other land in the game. Any enemy boats in pursuit directly behind the player will crash.
Many players are not aware that the button in the center of the steering wheel is actually useful. If you get partway through a stage without losing a life but want more of the weapon you picked up at the beginning of the stage (whether or not you're completely out of that weapon), you can press that button to call a second van and get replenished. It's also possible to use this feature to bypass missing bridges without going to the river mode, but timing is crucial and the actual passing of the bridge requires taking advantage of a little-known bug.