Star Trek- The Animated Series (1973), “The Time Trap”

Sent to explore the vast Delta Triangle (a veritable Bermuda Triangle in space where vessels have disappeared for centuries), the Enterprise encounters three Klingon ships. Hostilities commence. First a Klingon ship then the Enterprise disappears into a pocket universe, where both discover a Utopian society of cooperation comprising over a hundred races in trapped ships. Both newcomers are welcomed to join but must refrain from any form of violence whatsoever or suffer a harsh penalty. Only together can the Enterprise and the Klingon ship escape, but the Klingons have a devious additional plan in mind.