Wrong.
1. There are patients who will love to discuss this with you. TV, movies, comics, sports, music, and the like are used to find commonality with patients all the time. Maybe it will be to keep them calm and distracted during a procedure or just to win them over so they'll trust you when you recommend something and generally be less scared of their medical experience. I have zero cred with a huge age range of younger patients who you have an in with.
2. If you will bring up zombie movies in an interview, I know you're not telling it to me because it's professionally impressive. It makes you seem genuine and less nervous. It reassures me that you will do something to decompress outside of school/work. It raises the possibility that you will have something to talk about with classmates and will be fun.
On paper (GPA, MCAT, ECs, LORs) a lot of applicants are very similar. Zombie movies aren't going to be the crux of your application's success, but given two equal applicants, this little glimpse into who you are as a person can indeed make us think you'd be a better fit in med school than the applicant who does nothing but activities geared towards work/school. A positive med school and even workplace experience is conducive to everybody getting more from their education/work and becoming better doctors. And when given equally trained doctors, I am willing to wager that the happier one who can vent his or her stress will have better focus on my care and interaction with me when I'm a patient.