I know I have problems with pronunciation. My accent is very strong and it's typical Russian one. My sounds are very "hard" pronounced and there are a lot of typical Russian mistakes in my speech. I think, there are problems with pronouncing "w", "t", "th" and "h".
So, I found for example such mistakes in "wanted" and "was" words wich I spell as "v" sound.
I reduce some sounds and for example in the word "coast" I say [kost] instead of [kohst].
"Grand Canoyon" is a huge problem with prounanciation in both words. Instead of ['kænjən] I say something oppositional, emphasising the second word's part and it's "a:" in the first part instead of "æ". And I say "a:" as well in "Grand", but it should be the same "æ" instead.
As for "t" is just different. In English it should be exhalation while pronouncing, but I say very hard "t".