Ok first things first,
TV Ratings are usually wrong in both Canada, and USA. In europe they do ratings differently and they actually have a 75% zone of getting it right.
In Canada it's 55% and USA it's even worse at 46%
A good article on this in the USA today about 1 year ago. I will try to find it.
First off there is no question CFL viewership is way more than 600,000 a game. Remember ratings do not count people watching at bars/restuarnats. If there are 100 people in a bar, only 4 get counted. The ratings work on a 4/1 basis outside, and at home it's a 2/1.
If you look at the GOLF ratings, they are usually 250,000. That's way off. More likely around 500,000 for the british open.
The one sport that is given higher #'s is baseball. Blue Jays got a 400,000 plus on Sunday, that's too high. You also have to think not many people sit and watch a 9 inning baseball game. (I hate baseball it's not a sport, they should dismantle MLB yuk it's bad for our society) More likely the entire country would get a 150,000 for a full game. Seriously who would even watch baseball?
Soccer is very high also in this country because not many people watch soccer, or even watch a full game. But Soccer, Golf, Nascar, get shared #'s for scale meaning if you watch a % of the event, you would get counted. If you volunteer to get tested for viewership if you would watch a 50 laps of 250 in NASCAR you would get counted as 2/1 for ratings.
CFL and Hockey, even NFL get rated single viewership so it's harder to get ratings.
There is no question NHL, CFL, NFL are the highest rated sporting events in Canada, and it's not even close. Maybe #4 would be nationally telesised Golf, NBA-TNT games.
So I wouldn't pay attention to much in the ratings.
456,434 saw the football game last night. But did they count my neighbour who came over to watch the game?