When Sister Gertrude counts off calisthenics, per the audio, she gets it off beat as often as she gets it right, which is pretty bad, as it's a count of "One! Two! One! Two!..."
After Sister Gertrude hangs up the phone (at 1h05 minutes in the movie), she is back against the wall, the head of a crew member appears in his back, just for a second and hides very fast.