Anyone can send an anonymous message to this government agency and it will audit your business to make sure you are compliant. Have more than 50 employees? Make sure the copy button on your photocopier says "copiez" or you'll have to put stickers over it (true story, happened at my brother's pharma startup).
The sad thing is that most Montrealers have the attitude that "you're in Montreal, you should learn french." The problem is, this law goes far beyond that, and is a serious impediment for Montreal startups.