From my understanding, it is illegal to blacklist someone in terms of employment in Canada. So IF such a list was to exist, it'd probably have to be informal (meaning it'd be kept away from public and probably shared amongst employers).

My concern is, does such a list really exist? If it does, is there any way a normal person can check if they are on that list?

The thing is, I am a university student and just a year ago, I had a misunderstanding with a professor (whom had previously worked for the government and has close relations with significant politicians). He threatened to put me on a employment blacklist.

I've only recently contacted people at my university regarding this (as before I really didn't know what to do) and they didn't believe me. This particular professor most likely denied it. Since it was a year ago and the lecture hall having almost a thousand students, the peers whom I was able to get in contact with simply didn't recall the instance or I wasn't able to find the other students who attended the same lecture.

I am quite worried for my future.

Unless you are politically motivated and a threat to the Canadian government for some reason, I don't believe anyone can blacklist you. You didn't say what the misunderstanding was, but I can't imagine it being that bad and it doesn't matter who he is connected to, this cannot be done. So forget it and move on with your education.