Native English speakers, especially experts who should know better, insisting on pronouncing words as they are spelled. If you've been speaking English your whole life you might have noticed the language doesn't work like that.
Examples:
Dementia specialist on Inside Science who pronounced his own subject as di-men-tee-a.
News editor/producer on Feedback pronouncing ebola as ebba-la. Well, maybe in Spanish, but then it's spelled ébola, surely you've heard the word in your own news programme once or twice recently?
The one that takes the prize: guest on Inside Science (again) who kept saying "these woman are..." and "hundreds of woman", etc. On listening closer he was actually pronouncing the "-en" at the end, but otherwise identical to the singular. Seriously? It may be logically correct, but if 100% of everyone else doesn't say it like that, it's wrong!