The Fictional HMAS Hammersley has pennant number 82, The HMAS Huon as seen has the same pennant number (82) which is factually correct. The Huon is an actual Mine Hunter in the Royal Australian Navy with Pennant number 82.
HMAS Huon is seen alongside Hammersley offering assistance with Hammersley's broken fuel line. Its pennant number - 82 - is clearly visible, yet that number is supposed to be that of the fictional Hammersley. This reveals the same ship was used for filming. The same error is repeated after the "Huon" hits a mine.
When Luxton talks to Flynn on the bridge she's a Lieutenant Commander. During the fire drill she's a Lieutenant then when she's talking after the drill and for the rest of the episode she's back to a Lieutenant Commander.