10 More Times Star Trek Accidentally Filmed Things You Weren't Meant To See

The two-parter Birthright was one of the very few crossover episodes on The Next Generation. In the episode, the Enterprise-D docked at Deep Space Nine to assist the station with repairs, giving the two crews some time to chat with each other.

In the first part of the episode, Doctor Bashir came aboard the Enterprise and ended up working with Data for a while. Near the end, at about 38 minutes in, the two had a chat about Data's recent dreamlike experiences while walking down the corridor.

It's easy to miss, but at the beginning of this scene you can see Bashir wearing his typical black boots that he always wears with his uniform, but seconds later, when he walks away from Data, you can see him wearing what look like white tennis shoes. The cast would evidently sometimes wear different shoes when their feet were off camera, either for comfort or to reduce the noise of their steps.