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.