All those years in grad school and slaving away for tenure are finally worth it: I have taught people some phonology in a thread titled "Whose ass am I kicking."
It's possible that certain people from certain language backgrounds would have great difficulty with the difference
Possibly, but they have other worse problems. Probably the worst pronunciation difficulty for speakers of other languages are the two sounds (yes, there are two) spelled 'th' in English. These are very rare sounds in the languages of the world, so hardly anyone comes to English as a second language with any experience with them from their native tongue. You have probably noticed that nonnative speakers have trouble with those sounds, and maybe you've also noticed that children learn to pronounce these sounds late - it is typical for children to acquire rare sounds later in their development.
Just a little of what counts as a Fun Fact in linguistics for those who might care. Now, how about those cartoon cats?