I discovered something really interesting when playing Ghostbusters: the video game for the DS. The deleted parade level from the XBOX 360/PS3 versions is the DS port.
This is the is the level that Harold Ramis talked about in some of his interviews. I remember him being saying he was disappointed that Atari/ Terminal Reality cut this level out for pacing. A short clip of it can viewed in the first trailer that was released in December 2008.
Here is how the level plays out. Following the attack at the museum, the Ghostbusters are looking for the Chairman ghost, and follow him to the Macys Thanksgiving Day parade.
Walter Peck will not let them pass onto the parade route following the destruction caused at the Museum, so they follow the PKE readings down into the sewer. The chairman has taken refuge in a disused tunnel near the subway system, unfortunately there are barrels containing explosive materials present in the room he is in, and as Egon points out using the proton beams would cause a cave in. The Ghostbusters instead trick the crocodile monsters also present in this level into attacking him, which forces him to retreat to the surface, where the proton beams can be safely employed. The Chairman posses a turkey balloon(In the console versions the balloon was a giant dog.) and puts up a PKE force field to protect himself from capture. Ray points out by drawing him over to the helium tanks in the park, and opening the valves it will counteract his force field and make weak enough to be contained.
This level is defiantly one of the most fun in the DS version. The puzzles really make you think in order to defeat the chairman, and the jokes are some of the funnest of the whole game.
I highly recommend playing the DS version if your interested in seeing how the parade level mite have turned out if it was left in the console versions.