Imaizumi singing it himself in the bath during the stinger counts as well.
Kanzaki figuring out Onoda's name
Onoda: Is she a cop!?
The omake ends with Imaizumi volunteered into a box for Kinjou's magic trick, and Kinjou pulling out two absurdly large scimitars to presumably cut him in half. The title of the next episode comes up just as Imaizumi screams, and it initially reads "Trembling Imaizumi" before Izumida's name comes in from the side and bumps Imaizumi's out to produce the correct title.
In a Callback to Episode 1, Onoda convinces an injured Tadokoro to sing 'Hime Hime' with him as they climb the hill. Both the faces of Tadokoro as he is forced to sing along, and the other racers as the pair pass them while badly singing, are priceless. This doubles as a moment of awesome.