"I've been on sets where things weren't relaxed because someone was creating tension for no reason"

This quote by Kevin Spacey is referring to the environment on a film set. He is recommending that there are times when the atmosphere is not unwinded and this is because of somebody developing tension for no factor. This might be due to a variety of factors, such as a director or star sensation insecure or overloaded, or a crew member feeling underestimated or unappreciated. It could likewise be because of a lack of communication in between the cast and crew, or an absence of understanding of the project. Whatever the reason, it is clear that Kevin Spacey thinks that tension ought to not be developed on a movie set for no factor, as it can cause a stressful and unproductive atmosphere. He is suggesting that everybody should collaborate to produce an unwinded and efficient environment, as this will cause much better results.