Eric Roth’s original screenplay had some quirks that would have made the special effects in “Forrest Gump” far more noticeable, which Hanks, Zemeckis, and Roth discussed during a panel at USC in 2009 (via Cheat Sheet). He had Forrest interacting with an animated monkey, perhaps giving a nod to the incident in Winston Groom’s novel where our hero becomes an astronaut and goes to space with an unruly primate. Lieutenant Dan and Jenny also had animated extras too, with Dan followed around by a black cloud over his head, and Jenny adorned with a pair of angel wings.

How would that have worked out? It depends on the animation technique they used, but the latter two would have been fairly straightforward, even with the CGI of the time. A few years later, “Twister” gave us some weather effects that are still fairly convincing, so that might have taken care of the cloud.

As for Forrest’s chimp companion, we can perhaps glean some clues about how that might have turned out from the raucous gang of monkeys in “Jumanji,” which didn’t look especially realistic even at the time. If Zemeckis, who had brilliant form combining real actors with cartoon characters in “Who Framed Roger Rabbit?” in 1988,  had gone with the more traditional animated route, he might have pulled it off. According to Zemeckis during the panel, he suspected that work on “Roger Rabbit” was why the producers wanted him in the first place. Zemeckis recalled:

“Forrest always had Curious George as a talking monkey talking to him… I don’t know if this is true or not, but I always had the feeling that because I did “Roger Rabbit,” that’s how they sent me the script because they said, ‘get the guy who can do the cartoons and the humans together.’ The first thing I said was, ‘I’ll do this but all this cartoon stuff has to go.'”

It was a wise decision from Zemeckis, as the inclusion of a talking chimp may have irreparably broken the spell of the otherwise low-key special effects, not to mention making the emotional core of the movie far more ham-fisted. Less was definitely more for this enduringly popular classic, and Curious George still remained in the final film as Forrest’s favorite book.