Part of the great fun of copy editing is correcting people for mistakes they don’t know are mistakes.
Here are three favorites:
Flak/Flack
The first is the military term, related to bursting shells. The second is a derisive term for a press agent, spokesman, or some other such public-relations “professional.”
Gauntlet/Gantlet
The first is a glove. You throw it down if you’re annoyed with someone and showing defiance. The second refers to, in the words of John Bremner, “a lane between two lines of men who beat some unfortunate as he tried to run through it.”
This, you run a gantlet. Not a gauntlet. That’s what you throw down.
Momma/Mama
I never saw this mistake until I moved to Florida. The latter spelling is preferred by both Webster’s New World and Merriam-Webster’s Collegiate.
I suppose the first spelling has some use, if one regularly refers to women as “hot mommas.” I wouldn’t want to use “mama” in that construction. I don’t know who would use that description in a general-circulation newspaper, though.