Although Marty is annoyed at Bifficus' attitude, Jules and Verne warn that they could indirectly ruin Hill Valley as they could return to find no United States, finding that instead it would be under a still-existent Roman Empire. Ergo, there would be no way of knowing if Hill Valley would have been discovered by the Romans, or if so, whether the Hill Valley citizens would be oppressed as many people were by the Caesars.
Marty agrees to let Bifficus win, as he is instrumental in Caligula's rise to power. It was later revealed that Caligula earned the reputations of one of the worst emperors, and his disastrous policies helped to run Rome into the ground (as occurred 440 years later), thus ensuring Hill Valley's survival.
On March 3, 1986, Marty's history teacher was telling the class at Hill Valley High School the story of how Bifficus Antanneny was instrumental in the rise of Caligula, and how Caligula's disastrous policies directly lead to the fall of the Roman Empire.
- Back to the Future: The Animated Series - Episode 5: "Roman Holiday"
- Back to the Future (Harvey Comics) - Issue 3: "Roman Holiday"
- Back to the Future (IDW Publishing) - Issue 6: "Continuum Conundrum Part 1" (Marty's history teacher referred to a popular athlete that was instrumental in Caligula's rise to power, which is how Bifficus was described in Roman Holiday)