My kids are bilingual... they speak English and Spanish perfectly each without any foreign accent. Their favorite word is "burrito", because Americans can't pronounce the "rr" sound. The American version of that word sounds ridiculous.
When I was much younger I studied Arabic. They have two letters that to me sound exactly alike. My Jordanian friends were always playing with me because they knew I couldn't say, or even recognize, the correct sound.
I think this is pretty common when languages don't share the same sounds.