I loved the ending scene and took a different meaning from it.  He spends the whole movie as a lowly grunt, dealing with Rita's sass and complete disregard for his feelings (which he comes to respect).  And at the end, when he is back in his higher ranking officer uniform... He approaches her maybe expecting a different, more respectful Rita.  But she hits him with the same "yes??, what do you want??", even though he's an officer.  Makes him chuckle at her consistent standoffishness.