As reported on the Foreign Works page of this web site, under Australian law, the date in a copyright notice is presumed to be correct.  These are passages:

131 Presumptions relating to films
…
[In (2)(b), discussing articles or things, or their containers, [which] bore a label or other mark consisting of the letter “C” in a circle accompanied by a specified year and the name of a person.
(3) It is presumed that:
  (a) the film was first made in the year; and
  (b) the person was the owner of copyright in the film when and where the articles, things or containers were labelled or marked;
unless the contrary is established.

and

132C Presumptions relating to films
Presumption about film maker
…
[in reference to] articles or things, or their containers, [which] bore a label or other mark consisting of the letter “C” in a circle accompanied by a specified year and the name of a person.
(4) It is presumed that:
  (a) the film was first made in the year; and
  (b) the person was the owner of copyright in the film when and
where the articles, things or containers were labelled or marked;
unless the contrary is established.

(from the Copyright Act 1968, Act No. 63 of 1968 as amended, prepared on 26 July 2007, available from https://www.comlaw.gov.au.)