At the time of leaving for Hanging Rock in the cart, before they go there are 17 young girls in front of the steps; during the journey there are only 13 of them in the cart; at the foot of the Rock there are again 17.
Miranda cuts the Valentine's Day cake with a clean kitchen knife. However, the next shot shows the cake cut down the middle, and the same knife lying beside it clean and bare, as if it had never been used.
When the Gardner is showing Albert that some plants move while in the greenhouse, his eyeglass strap is on the right side of his face and in the next shot it moves to the left.
When Tom is brought down from the rock he has a dressing dead centre of his forehead with blood dead centre of this. A few scenes later his wound is more to the right side of his forehead.
The movie takes place in February 1900, 11 months before the Australian colonies federated and 11 years before the creation of the Australian Capital Territory within New South Wales. When Mrs Appleyard addresses the gathered pupils to communicate the merciful deliverance of their classmate Irma, the NSW map behind nearby Miss Lumley clearly shows the existence of the ACT (defined in red).
Although accurately following the book (and a good indication that this is indeed a fictional story), to make the days and dates actually match up, you need to either move to 1903 or 1874, as those are the closest years that had Feb. 14 on a Saturday (and March 27 on a Friday)
According to the voice at the end credits, March 27th 1900 was a Friday, when in actual fact it was a Tuesday.
14 February 1900 was a Wednesday, not a Saturday. While this seems to be a factual error, it could be a subtle hint that this is a fictional story.
In the standard disclaimer (that all characters are fictitious) that appears in the final credits, "fictitious" is misspelled as "ficticious."
As the drag pulls out of Woodend, power poles are seen to the left of the screen, also, a television antenna is also seen on the roof of a house in the same scene.
Modern foundation garments are seen quite clearly through the girls' white shirts in many places when the camera trails behind them as they move about the rock.
The bridge of Marion's eyeglasses sets near the top of the frame; prior to the 1920s, eyeglass frames were manufactured with the bridge vertically centered between the lenses.