'Got bitten' is standard English. 'Got bit' is non-standard. You will hear people say this, but it sounds ill-educated. Put it in a similar category to double negatives, 'ain't' and 'He don't'.

Tiger, "bitten" is the standard form though we see "bit" being used at times. He beats his co-workers whenever he flies into a rage. (present tense) *Errata: He bites his co-workers whenever he flies into a rage. (Thanks to Nanren for pointing that out.) He bit his co-workers when he flew into a rage. (simple past tense) We knew that he had bitten his co-workers in the past. (past participle form)

"Bit" and "bitten" are both acceptable. "Bit" is more informal but very widely used where I am.

For another perspective from the United States: The American Heritage Dictionary lists "bit" as a possible past participle, in addition to bitten, with no usage note that such use is non-standard. A "bit" about The American Heritage Dictionary: Its stance on a number of grammatical issues can be, admittedly, liberal sometimes. But, its usage panel is a list of who's who of Americans working in the fields of linguistics, literature, criticism, etc. Generally, it will include a "usage note" if a word is considered non-standard or if there is a debate about a usage. These notes are wonderful, as well as are the pictures in the hardcover version (the online version still has the usage notes). The dictionary is actually great reading. Highly recommended!

You are correct. "She got bit" is yokel, informal, incorrect. :)