Okabe gives Kurisu several nicknames over the course of Steins;Gate, only calling her by her real name in serious situations. Kurisu's most frequent nicknames are "Assistant" or "Christina" (by adding '-tina' to 'Kurisu'), but Okabe also calls her "The Zombie", "Money Bags", "@Channeler", "Mongolian Spot", "Experiment Loving Girl", "Perverted Genius Girl", "Experiment Loving Perverted Genius Girl", "Celeb Seventeen". Even though Kurisu seems to hate being nicknamed, she thinks it's hopeless to point that out to Okabe.
Moeka can apparently type and send SMS's at the speed of normal speech, which leads to Okarin calling her "Shining Finger".
Okabe's nickname for Ruka regardless of gender is "Rukako", "-ko" is typical ender of many female given names in Japanese.
Okabe claims he has an IQ of 170. For reference, 145 is considered genius level of intelligence.
The story references and builds upon the real "John Titor case" from the turn of the century. A mysterious Internet persona who posted on Internet message boards claiming to be a time traveler from the future. The CERN research institute and the IBM-5100 computer (dubbed SERN and IBN-5100 respectively) are also both real.