Check this out, I lived in Arlington Va when they were filming this movie, one day a dude knocked on my door and said he was from Paramount and wanted to use my 1969 chevy van in the movie, they paid me $500.00 , gave my van a complete paint job and bought a brand new set of original equipment tires and wheels, and used it as a channel 4 news van in the scene at the reflecting pool where Forrest is making a speech and jenny is in the crowd and they run to meet in the reflecting pool, you can see my van for about three seconds as Forrest is walking to the stage to make his speech he walks by it on its drivers side, it is a two tone blue/white flat nose sportvan, now, here is a top secret blooper in the movie, on the day of filming they had a flat tire on my van and put on one of my old tires with a 1972 era pontiac rally wheel on the rear of the van, I noticed it right away the first time I watched the movie
They also tried to shoot a scene with a bunch of people on the roof of my van and buckled the roof, the sheet metal popped back out and was not damaged but they broke the fragile ceiling trim on the interior, they paid to have it fixed and I got a nice new headliner out of it.
oh, yeah, in that same scene where it looks like there are thousands of people at that rally, there were only about a hundred people standing tightly packed in a small square.