The site's authors note that although there are resources they believe are better, "W3Schools has put a lot of effort into positioning itself at the top of search results and, despite our efforts (such as the PromoteJS initiative), appears to be there to stay." Since the site went up, several issues have already been fixed and W3Fools notes those with strikethrough.
Here are the resources W3Fools recommends as alternatives:
W3Fools is calling on W3Schools to wikify its tutorials so that readers can fix mistakes. W3Schools does have an e-mail address for corrections. When asked whether W3Fools had contacted W3Schools, co-author Boaz Sender replied "Yes, and I believe a number of them have been made." Update: Another of the authors, Paul Irish says the authors did not contact W3Schools ahead of time.
W3Schools did not respond to our request for comment. The company is based in Norway and the request would have arrived in the late Friday afternoon there, which may explain the lack of response.
Update: W3Schools has responded.