Up until about a year ago, on this message board, I also hadn’t even heard of the spelling or pronunciation “Rigmarole”. Upstate NY and Florida. Although it’s a word that only comes up a few times a year anyway.
Right, but Americans, especially, start to make the mouth shape for the “r” early…which in an unstressed syllable (where the vowel is pronounced as a schwa, at most), means during the previous consonant.
Take the word “bird.” You make the “r” mouth shape at the same time you pronounce the “b”! Check it out. Start to say “bird,” but then stop yourself – indeed, you’re making the “r” position (tongue against back molars) even before you sound the “b.”
I guess you guys didn’t search the other entries. My copy does contain one “rigamarole” in a quotation for another entry (kragdadig):
So it seems that yes, “rigamarole” is an attested spelling going back as far as 1949.
… while being driven around by their Realator.
Search the other entries? Um, I have a paper and ink copy of the OED. We used to call such things “books”. Are you suggesting I quit my job and spend the next few years looking for that spelling?
What do you think I’ve been doing for the 8 years since your original post? 
Many are called but few are chosen.
Surely this is just a matter of edumacation?
Rigamarole is a perfectly cromulent word.
I think you mean “caromulent”.
Rigatoni.