I've never had any problems like you mentioned with MRI's.
My worst was I had to hold still as a statue litterally when they did 3 detailed scans on the optic nerve. The region being scanned was so small I did not have any give in movement. Try holding your eye still! It's harder than it sounds. Thankfully there was some grime on the light cover I could use to focus at.
I was in a newer version of the MRI about a year ago. Still the "tube" version however not as elongated and much wider that the versions I had been in before.
I'm not sure what the "dye" or contrast consists of (whatever they call it). Usually it's the point of application where some people may have issue. Other may show a mild reaction. I have not heard of anything major; nor have I had problems with it.