This comprehensive PDF report is an excellent introduction to what is and what is not covered by a film producer's E&O insurance policy.
The author is an attorney who has spent a considerable amount of time working with the Canadian film and television industry. She has represented international film insurance companies for over 30 years.
Also discussed in the article: Overview of Clearance Procedures
E&O Insurance 101 & How to Protect Your Film Project
Are you paying for the coverage you need?
Distributor Errors and Omissions
How much of your film is copyright-able?
To get or not get permission: The Social Network
A production lawyer's guide to obtaining E&O insurance and preventing litigation