Based on what Zak Penn says, Spielberg wasn’t looking to include this reference to Jurassic Park that was in the original script.
Penn is also sure to clarify that the T-rex that appears early in the movie is explicitly not supposed to be the one from Jurassic Park but is instead simply a dinosaur.
Ultimately, the decision not to use the velociraptor worked out, as the logistics of throwing a dinosaur out of a car was going to end up being a problem anyway.
Steven Spielberg had said during the production of Ready Player One that he was generally against the referencing of his own films, only allowing the Delorean from Back to the Future, which he produced, to make the cut.