An ant may be seen crawling on their table as well.
The name seems to a reference to the popular fiction character "The White Rabbit" from "Alice in Wonderland". In the story, the character is first seen wearing a waistcoat, running along hurriedly, looking at a pocket watch and saying "I'm late! I'm late!" in one way or another (Katherine tells Vincent at the Chrono Rabbit that she is late, referring to her possibly being pregnant). The rabbit is most often associated with his timepiece and that fact that he is constantly noting tardiness. The name "Chrono Rabbit" probably comes from that fact that the white rabbit is often associated with time, given his first appearance to Alice, and has actually been a symbol for "time" in other media as well.