Jenny Baird was horrible

I enjoyed this movie somewhat, the script, humor, etc were all good, but my problem is with the acting. The actors and acresses don't seem believable as people of the 1950s. Some of them did a good job. Eric McCormack and Jody Thompson did very well. The actors who played the owner the diner, bubba and his friend, and several other bit parts were excellent. They seemed like actual 1950s people. The "cool cat", sheriff, deputy, short-haired girl and her boyfriend were bearable. But Jenny Baird is the one that spoiled it for me. Never, even for a second does she seem like a 1950s person. Her hair style even looks completely modern. Does anyone else think that some of the casting choices were wrong for the movie?