Should I attend a job interview after I've already accepted another offer? I applied for several postdoc positions recently. One made an offer which I accepted. Since then I've been invited for an interview for one of the other positions. Is there any benefit to attending? Is it an opportunity to make potentially useful contacts (in a relatively small field)? I should add that I have no experience with academic interviews (the position I secured was through contacts). Expenses will be paid.
Once you've accepted a job offer, you are supposed to inform other places that you've applied that you would like to withdraw from consideration.

If they still want to invite you over to give a talk knowing that you can not be considered for the position, go ahead. But, you must tell them.

To do otherwise would be a serious breach of ethics. You do not want to gain a reputation as someone who engages in unethical behavior (don't assume they won't find out).