Also:
There's another vowel sound (technically a diphthong) used by Scottish speakers (maybe more a West Scottish thing) that most often trips up actors approximating a Scottish accent.

in most English regions, the words "tied" and "tide" are pronounced the same.

Apart from the North-East, in most places, "tied" is approximately "taa -eed" "tide" is more like "tuh-eed", although it's more of a central vowel sound than "tuh"

The same difference is found in word pairs like sighed/side, pried/pride

it's a tricky one and I've never worked out how it arose.

The people who get it wrong, often pick one of the sounds and use it all the time. Dead giveaway.

And another thing: Gregory Peck in a movie called "Billy Two Hats" playeda Scots gunfighter in the Old West. Possibly the worst Scots Accent (apart from Scotty in Start Trek). He keeps on talking about his "goon" when he means his gun. I can only assume that no-one wanted to correct him.

Cheers

Steven