In the opening scene in the hotel, Mathew Newton is wearing epaulettes showing two and a half rings - the rank of Lieutenant Commander. Later when outside his jacket has one ring, the rank of Sub Lieutenant.
All three officers are shown wearing their medal ribbons on the right breast. Earned ribbons are worn on the left breast. Deceased person's ribbons may be worn on the right breast (father for instance), but only on such occasions as Anzac Day etc.
Toby Schmitz's character (Dean Lieberman) has one thick and one thin ring on his sleeves. No such rank exists in the Royal Austalian Navy. The rank shown is that of Lieutenant Junior Grade in the US Navy.
Award ribbons (and medals) are worn on the left breast, not the right.
Ewan Leslie's character (Sam Fisher) claims he will soon be promoted to Petty Officer when his epaulettes show the higher rank of Chief Petty Officer. However, these are enlisted (non-commissioned) ranks, whereas Fisher is actually a commissioned officer with the higher rank of Sub-Lieutenant.