Beam Me Up, Scotty!: Dante referred to the poem simply as his "comedy." The title The Divine Comedy was not adopted until later.
Speaking of which, Star Trek: The Next Generation said that Dante said something along the lines of "The hottest place in hell was reserved for good men who let evil happen." First, the center of hell is ice. Secondly, it's for traitors; people who are completely neutral aren't even allowed in hell, and their punishment is to go and be stuck between hell and purgatory, desiring any respite.
That might actually be the point. Good men who just weren't willing to commit themselves are in the bit of Hell furthest away from the ice. Thus, arguably, the bit that should be hottest.
Neon Genesis Evangelion fans are famous for their "four barons of hell" theory about the Evas' design. The most commonly cited source of this is the Inferno. There are no four barons of hell.
Science Marches On: In Purgatorio, we learn that the island of Purgatory is the only piece of land in antipodes, surrounded by a huge ocean that covers one full hemisphere. To his credit, Dante always remembers that the sun would be to the north in the antipodes. (And remarkably enough, he describes a constellation of four bright stars that sounds suspiciously like the Southern Cross; he couldn't possibly have seen it, or even spoken to anyone who had. Critics generally think it's a metaphor for the Four Cardinal Virtues (fortitude, temperance, justice and prudence) illuminating the life of the penitent sinner.)
Paradiso features a geocentric universe...sort of.
Averted in one noteworthy case : Inferno and Purgatorio clearly features a round Earth (proving that the idea that people once believed, especially during the Middle Ages, that the Earth was flat is completely wrong. The fact that the Earth is round is quite obvious to the senses and easily proven through basic geometry known since Antiquity).