Character mistake: Will's tax demonstration to his volunteer staffers is incorrect. He applies the various tax rates to the entirety of each salary range. The person who makes $150K and is in the 36% rate...in his example he has them paying 36% on their entire salary, not just the portion of it that puts them ahead of the next lower tax rate. If the tax rate jumped to 70% at income of $1M, and a person earned $1,050,000, they wouldn't be paying the 70% rate on all $1,050,000 of their income, only the last $50,000 of it. Will's example makes it look like they would be.
Continuity mistake: Toby, Sam, and Amy are sitting at a table talking - Amy's eyeglasses are on the table in front of her - when Toby asks Charlie what's on the TV, the shot shows her glasses have rotated 180 degrees and her arms have noticeably changed position.
Continuity mistake: In the Sunday Morning segment, at a White House meeting, a grey-haired woman is sitting at the table with her hand on her bottle of water - the next shot shows her hand several inches away, with no time for the change.
Chosen answer: A really annoying innate lack of sense. My friends and family say the same thing all the time, and I'm endlessly trying to correct them. I think people just don't know any better and (ironically) couldn't care less that they're speaking incorrectly.