This is a problem which worries me a lot. I am well aware that the use that the archive gets means that inaccurate statements in the archive will be read by many, copied by many, and may become accepted as the truth.
What can I do about this?
1. Worry about it!
2. Get material checked.
3. In fact the archive is read by so many people, and by so many experts, that we get considerable feedback on the material. This covers a range of things from reporting spelling errors and typos to informing us of new research which suggests something different from what has long been accepted.
In fact the web has advantages. If Jacobson's birth date is wrongly given in a book it is hard to correct this short of new editions etc. The web material can be improved continuously.
How can it be used for teaching?