I just bought a ticket for a trip back to Korea this fall. I feel guilty for not leveraging more of the culture there in my writing; usually it's the food that sneaks in, the snacks sold from stalls on the street. After all, buying a bag of silkworm pupae is going to feel more natural in a fantasy story than doing the same with a hot dog. —No? Okay, perhaps not boiled bugs, but I have occasionally given my characters chopsticks instead of having them pull out ye olde trusty dagger to start carving a haunch of boar.
One of my WIPs deals with a nomadic tribe in the desert. I've read as much as I could get my hands on about the Bedouins and the Tuareg, but there's never going to be an aspect of their cultures that I can simply reach out for and sprinkle into the story for a little more flavoring. There's always going to be painstaking research and fact-double-checking behind anything I write for this.
I think this may be part of what they mean when they say, Write what you know. Even the faithful steed of standard fantasies is often mishandled.