According to an interview with Shinichi Watanabe in Newtype USA, the end theme, in which the dog Menchi barks the song into a microphone, was recorded with voice actress Satomi Koorogi kneeling on the floor like a dog, with the microphone lowered to her level.
The original North American voice actress for Excel, Jessica Calvello, damaged her vocal chords while doing the dubbing for Excel Saga Region 1 DVD #4, necessitating her replacement by Larissa Wolcott starting with episode 14.
At the end of the second episode on Region 1 DVD #1 there is a joke added by the ADV production team, which requires that the viewer watch both the original Japanese and the English dub versions simply to notice it. In the final scene of Episode 2, Excel is being interrogated by a band of soldiers. In the dub version, one asks her "What is your purpose?", to which she inexplicably replies "A big fish?" In the original Japanese, her answer is a simple "I don't know" - but the Japanese actor playing the soldier speaks in English, and does it so badly that his question comes out sounding like "What is a porpoise?"
Episode 26, "Going Too Far", was intentionally designed to be too controversial to be shown on TV. Among other things, the episode features nudity in the opening credits and Hyatt spewing ridiculous amounts of blood (instead of just bleeding like in other episodes). The episode is included on the final volumes of both the Japanese Excel Saga DVDs and the region 1 DVDs released by ADV.
Disc 2 of the Region 1 DVD has several easter eggs, including at least three "commercials" for Menchi-based foodstuffs. Every menu on the disk has one or more "folder" icons. Various combinations of arrow keys will light them up; trial and error will find them very quickly. Almost all of them show some kind of short clip.
Much of the content of the original manga by Koushi Rikudo was considered too raw for television broadcast, and so Watanabe and the rest of the production crew tried to improvise on the material's bare bones. As a running gag on this fast-and-loose interpretation on the manga, someone suggested a sequence at the beginning of each episode where Koushi himself approves the changes.
In keeping with the anime tradition of "theme naming", several characters have names taken from hotels and other guest residences: "Excel" is a chain of hotels in Japan; "Hyatt" is of course the American chain; there are at least two hotels in Tokyo called "Il Palazzo" ("The Palace"); and "Ropponmatsu International House" is in Fukuoka, just to name a few.
The title of episode 4 is "Love Puny". Originally, in Japanese, this title is a pun which unfortunately has no way of surviving the translation into English - the Japanese word for "puny" is "henachoko", shortened in the title to "hena" - making the title "Love Hena," a reference to popular romance-comedy anime, "Love Hina."
In Episode #18, "Municiple Force Daitenzin", the newscaster on the monitor in the Countermeasures center is supposed to be the scrapped version of Puni Puni Poemy. However, on the lower right of that same scene, you will see a drawing of the real design of Puni Puni Poemi, bell and all, on a piece of paper sitting in front of the countermeasures head.
In Episode #19, "Menchi's Adventure Part 2: Around The World In 80 Hours", while Ann Anzai's Grandfather was being operated by HOUNDS Scientist, you noticed that he had on the Kamen Rider 1 costume, without the helmet of course, while laying on the operating table.
The setting of F City, F Prefecture is named after the real-life town of Fukuoka City, Fukuoka Prefecture in Japan - which is also home to a convention center called ACROS (an acronym for Asian CRossroads Over the Sea).