When Bernie tests the ladder just before the 57m mark, it causes the picture to shake - clearly the camera used for the aerial view was disturbed by the movement. Yet this may have been deliberate to add some tension to the scene, however illogical.
When Bernie is talking to Dave, his pint glass goes from roughly half full to nearly empty, just in time for Dave to offer to buy him a pint. However, it's possible that Bernie was drinking while the shot was on Dave.