Michael Trucco, who played the fantasy man in Mary's book, was also in Season 2 of The Big Bang Theory (2007), specifically The Bath Item Gift Hypothesis (2008). He played David Underhill, a scientist who Leonard looks up to, but then also jealous of when David goes on a date with Penny.
Sheldon, during his in-class discussion with Dr. Sturgis, mentions the moral dilemma of cloning dinosaurs, the plot of Jurassic Park (1993). Though it lacks specific details, this episode takes place in the autumn of 1992, as evidenced by Sheldon being in class and the later episode Pancake Sunday and Textbook Flirting (2023) that features the premiere of Star Trek: Deep Space Nine (1993), which was on January 3, 1993. Jurassic Park, the film, wasn't released until June of 1993 and the characters may not have known about the film being in production. However, it's possible they knew about the best-selling and critically well-received 1990 book by Michael Crichton.