Gadget is a female mouse.
Her eyes are blue, while the color of her hair has frequently been a topic of discussion as it changes from episode to episode. In many episodes her hair appeared to be orange in color. In still others, it showed up as being a strawberry blond. At one point, Tad Stones, the producer of the show was contacted by a fan and gave this explanation:
"I believe the intention was sandy blonde. Because we work with a limited color palette, we pick the closest color to what we want. There was no intention of adding red. I did the first paintings of Gadget and she was completely blonde wearing blue coveralls."
She usually wears a pair of lavender mechanic's coveralls, a purple belt, and a pair of blue goggles which she keeps on her forehead when she doesn't need them. A white shirt can often be seen under her coveralls, but it is even more inconsistent than her hair, sometimes disappearing and reappearing within one scene. Though she can occasionally be seen in different outfits matching the situation, she never wears a dress or make-up unless it is part of a disguise.
Gadget's personality was based upon the inventive female character Jordan in the 1985 movie, Real Genius. She's a combination of the "cute girl next door" combined with an obsessed and quirky inventor. There are a few people she doesn't like, but those few are typically villains. Gadget has a natural warmth about her that makes everyone welcome and pleased to see her. She's very loyal to her friends and frequently goes out of the way to help them.
At the same time, Gadget constantly is thinking. As exhibited in the episode Gadget Goes Hawaiian, she has trouble focusing on just one way to do things. However, once her focus has come she can invent at a staggering pace—for instance her armored gyromobile in The Case of the Cola Cult.
Gadget has her quirks. She thinks so much from an inventor's standpoint that it tends to make her naive at times. She's upset Chip and Dale's romantic advances more than once, simply by not understanding what it was they were after.
When Gadget's excited about her inventions she's known to use scientific jargon freely and talk at an extremely rapid pace. This tends to leave anyone listening to her clueless as to what she actually meant, but it never seems to bother her.
Gadget can be angered. As we saw in Kiwi's Big Adventure, The Case of the Cola Cult and Dirty Rotten Diapers, Gadget has a limit beyond which her cute veneer is lost and she becomes, well, aggressive. Woe to the villain or anyone else who manages this feat, because once Gadget's riled she's a juggernaut—thankfully, such incidents are rare.
Accepted Fan Fiction Conventions
"It should work with no problems."
In many fan fiction stories, there is at least one scene in which Gadget says about her recent invention that it "should work with no problems." Although this looks like a quote from the series, it is none. Instead, it combines two similar quotes. One of them is the word "should" which Gadget uses when she is not completely certain if her creation will work the way it is supposed to. And since not few inventions of hers have failed though they "should" have worked, this one word will always alarm the Rangers. The other quote is "no problems". There have been enough situations which Gadget described with these two words, and which then turned into the opposite, to give this saying the same effect as the word "should". The fan-made combination of both doubles this effect, however with different outcomes in different stories.
Gadget's love life
Gadget's love life is an issue explored in a large amount of fanfics.
Another issue frequently dealt with in fan fiction is her family or reasons for a lack thereof.
Her fondness of strawberries
Gadget's love for strawberries is shown in quite a few pictures, although the show never showed any food preference. This trend was apparently started by Michael Demcio. (Could someone please confirm this?)