Accidental Innuendo: This infamous picture of Imaizumi and Onoda. note Due to Onoda's hand placement of the flask being close to Imaizumi's crotch, also not helping that Imaizumi is showing off his abs
Dadokoro for Tadokoro, due to his Team Dad tendencies. Fans sometimes add Mamakishima to the family.
T2 ("team of two" or "team futari" in Japanese fandom) for Teshima and Aoyagi (both the team and the ship).
Izumida is, of course, "Abu-kun."
Kuroda is "color-swapped Arakita," due to similarities in both design and personality, not to mention the same role in the IH team.
Genius Bonus: Izumida names his specs Andy and Frank, which is likely a reference to the professional road bicycle racer Luxembourgish brothers Andy and Frank Schlek.
Jerkass Woobie: Midousuji. His backstory is very tragic and gives watchers plenty of reasons to pity him, but his present actions often come out as petty and cruel.
THE PACK: the mass of cyclists who failed to get high rankings places on day 2 of the Interhigh and so are now riding as a huge group to ride at a high consistent speed to catch up to the other cyclists... that is played more or less as an unstoppable eldritch horror in the anime.
Arakita's withdrawn from the team in the third day of Interhigh can have this kind of effect for some, mostly because his teammates act like he died or something (Manami is especially guilty of this, going to the point of saying Arakita was a great person. In the past tense). But for the majority, it's still a very convincing Tear Jerker moment that crowns his Character Development, so there is a bit of Narm Charm element there.
The first race between Kinjou and Fukutomi consist largely of them saying their respective catchphrases ("I am a man that never gives up" and "I am strong"), each other's names, and explaining rules of the race to each other.
Narm Charm: The whole idea of the power of the Love Hime song is utterly hilarious and strangely uplifting.
Padding: Due to its popularity in Japan (in its heyday it is always near the top of the TOC rankings along with Baki Dou in Akita Shonen Champion), the mangaka is able to extent the Interhigh match as long as possible, taking nearly 150 chapters just to finish the entire first year of Interhigh, some of the pages consists of cyclists riding to the finish line meters by meters until the very end