Is it a mistake to sell a chapter of your finished book as a short story to a fiction magazine? The magazine claims they "buy first North American and foreign serial rights and an option on anthology rights. All other rights are retained by the author."Does this mean we could lose access to that chapter if the book is published?
The word you're looking for in the short story contract is "non-exclusive".
If it's not there, make sure they have exclusive rights for a specified time period, and not longer than year.
This is actually a very good thing. It counts as a pub credit, and you'll mention it in your query.