I actually attend University of Toronto and I only know that we have up until a certain date to drop a course without it appearing on our transcripts. I had a friend who under special circumstances, dropped a course after this date and the best UofT could do for her was to have the credit not count towards her GPA but they couldn't remove it from showing that she dropped it on her transcript (some letter designation indicated it was dropped but didn't count). I had never heard of that happening before she told me, and she made it sound like she had to go out of her way to get it done, so based on that I'm not sure how good that will look. But different schools have different rules (and one would hope that they acknowledge that fact). I'm sure if you only did it once or twice it doesn't really matter.