As of "Milli Saves The Day", Milli is the only member to go on a mission alone. That is the only episode containing solo adventure and she is the only member who have done that.
"Milli" happens to a prefix meaning "By the thousandth" or just "thousand". It may also be based of the word "chameleon" since she can change colors/colours from her dress kind of like a real chameleon.
Milli is the only main character with definite age (She is 6 years old). Other characters' ages are indefinite. It predicts that the age gap of Geo and Milli is one year.
For some reason in some Team Umizoomi products, Milli's clothing has a more reddish tone.
Sometimes Milli's dress would deploy like a parachute.
In one episode, it is revealed that without her helmet, she has very long red hair.
Out of all the members of Team Umizoomi, so far, Milli is the only member to not be in trouble. Bot was in Crazy Skates while UmiCar was in The Great UmiCar Rescue.
According to polls, Milli is the favourite member of Team Umizoomi.