While only 24 episodes were aired on TV of the first season, it is actually 26 episodes long. The last two episodes have been released with a Japanese DVD in April 2006. In some countries, these two are part of the regular broadcast.
The last two episodes of Season 1 are unrelated to the main plot and do not continue the story. The first special episode, released on H&C Region 2 DVD Vol. 5 as Chapter L, covers the story of Lohmeyer/Romaiya-sempai aka Ham-Guy, who appeared early in the manga, but was not featured in the main anime. The second special episode, Chapter F, which was released on DVD Vol. 7, features Fujiwara Design, the company where Takumi Mayama formerly works at.
The names of the Presidents of Fujiwara Design are Mario and Luigi, the same as two of Nintendo's mascots.
The second opening sequence, from episode 14 onward, also features an homage to (or imitation of) the work of an earlier animator. Specifically, some of the swirling abstract shapes in the background, preceding the appearance of the main title logo, are lifted directly from "Studie Nr. 7," a piece of experimental animation crafted in 1931 by the German artist Oskar Fischinger.
The opening sequence (from episodes 1 - 13) is inspired by an artwork called "Food" by Czech animator Jan Svankmajer. The opening sequence is one in a number of works that its award-winning director has been accused of 'stealing from existing artists'.