The interior door in Keel's surgery resolutely refuses to stay closed.
(at around 38 mins) A crewman can be clearly seen in the top right corner wearing a head set, he then ducks very quickly out of the scene.
Carol points to part of the circus poster dedicated to "Vera... whose death-defying dive of ninety feet will astound you!" Keel looks at this but somehow adds her surname as he muses, "Vera Korsova..."