The kendo style Setsuna Sakurazaki uses (Shinmeiryuu) in the manga, is what Motoko, from Love Hina, uses. The settings in Negima are from actual places in the Japan, although some locations have been modified for the story. Some examples are: Mahora Junior High School - The school building is actually the JR Fukaya Station in Saitama Prefecture. Mahora Junior High School Dormitory - The school dormitory is actually the Tokyo Metropolitan University in Hachiouji-shi near the Keio-Sagamihara Line Minami-Oosawa Station. Mahora School City Starbooks Coffee Shop - The coffee shop is actually the Starbucks near the Keio Line Seisekisakuragaoka Station.
In the appendix of tankoubon vol. 5, Akamatsu explained that character Yue Ayase was designed by his former assistant Ran Ayanaga, who has worked independently as the artist of Read or Dream. The similarity between Yue Ayase and Hisami "Hisa-chan" Shiishi, a character in the R.O.D universe, is very evident.
In the official translations of volume 1, "english master" Negi mistakenly says its time to move onto "verb declensions." Verbs are conjugated, not declined.
In volume 11, look for a Yuffie and Tifa cosplay from FF7 during the cosplay contest segment of the festival.
In volume 5, the shirt that Asuna is wearing as they infiltrate the temple has the words "Run Lola Run." This is the title of a German film released in 1998.
In volume 8, as Chizuru is dragging Kotarou off to the bath, Natsumi can be seen putting her hands together and saying "Namu." This is the beginning of a Buddhist saying, "Namu Amida butsu," which is used to venerate a name that it precedes, presumably Natsumi is praying for Kotarou's safety.
Chachamaru saves her images as *.TIF. This is shown when hakase tries to find out who Chachamaru is in love with
add on to the volume 11 trivia: if you look closely you can also see a cosplay of plenair, the mascot for nippon ichi software and a character in the disgaea series. she kinda jumps out at you, but its not too hard to miss and it is not stated in the back of the book
On page 101 of volume 2, the metatag "Love Hina," is displayed in the html coding, a reference to one of Ken Akamatsu's older works. In volume 9, chapter 76 Ako Izumi appears with a shirt that has imprinted the words "the place promised in our early days" the same as one of the title translations for Makoto Shinkai's 2004 movie Beyond the Clouds.