I oddly discovered this as well (not something I thought about) when watching a playthrough video for a boardgame (Brass: Birmingham: https://www.youtube.com/watch?v=Lzxf4tfq9as ). In there, he says "iron" as it should be said given the letters in the word. My wife and I are somewhat working to actually say the word that way now.
The 'r' and 'o' are transposed: it's pronounced 'iorn.'
According to this[1], that's only in the USA... British English appears to drop the 'r' entirely (that's why I never hear it as I've lived in Europe and Australia)... and the American pronounciation seems so odd, is there any other word where the 'r' and the vowel are swapped like that? I know only one in British/Australian with "centre" being pronounced "center", but can't think of any others.
[1] https://dictionary.cambridge.org/dictionary/english/iron
> British English appears to drop the 'r' entirely
Yeah, but the Brits make up for that by stuffing a lot of extraneous 'r's in between other words.
(TBF, that's a kind of sensible simplification of pronunciation: it's used when one word ends and the next starts with a wovel, to ease the transition.)
Another one I, as a non native speaker, find odd, is "iron". People just say it as "ion", dropping the 'r', right?? At least that's what I hear.