The family look through windows as new neighbours move in next door. Hal's fingers/thumb (right hand) are in one position when viewed from inside and another when viewed from outside.
At the dinner table we see Hal with a knife in his right hand and a fork in his left. Lois say: "They are officially the worst neighbours we have ever had." Then we see Hal pass the fork from his right hand to his left.
Francis enters Commandant Spangler's room. Spangler's hat hangs on the clothes rack in different ways (dependent upon camera).
Most times, Francis has no rank badges on his shirt epaulettes. However In the song rehearsal and when he enters Commandant Spangler's room he has a single bar on each shoulder of his dress uniform.
The hired gardener cuts Lois's hedge but the hedge appears uncut and full size in the closing scene.
The remnants of the crushed garden Gnome that Dewey stomps on are clearly paper as opposed to clay. This is also obvious when Lois is picking up the garden decorations and she picks up the gnome with one hand. A clay gnome that size would have required two hands to carry due to its weight.
(About 14 min 07 sec) A Steadicam can be seen moving out quickly of the right picture frame.
At 11:55 a large black shape appears behind Spangles he addresses the cadets. In other views of its not there.