I found this Blooper shot when making a screen capture at the beginning of the I Love Lucy episode “The Business Manager”. To the right of the shot we can see a member of the production crew, possibly a camera operator. To see this you have to pause the action  at the very beginning of the first scene.

Ref: http://www.amazon.com/gp/product/B00ECHWAAU/ref=dv_dp_ep13