I think we had better point out that the company may not think it is work: it will be a "team-building course", which is essentially training in "soft skills" and team dynamics, by means of games, discussion and informal lectures, most probably in a residential situation in a hotel or a dormitory. Many companies believe that they are giving the staff free continuing education by inviting to such a course, which is often expensive. "In the country" means it is away from the office in the countryside. For the employee who is writing, it is overtime work. So you are looking at two different points of view. You are looking at western corporate culture.

That means you're not paid by your company for working the extra weekend---as opposed to your normal working days from Monday to Friday.