The slip rule exists in most jurisdictions in various forms but essentially allows for the correction of orders or court certificates. In the ACT the correction can be made by application or on the court’s own initiative and practice allows for the correction to be made in chambers.
Whether or not a Court has the power to correct and effectively alter a final judgment in order to correct a mistake arises frequently and there is a common law power in addition to the rule. As stated by the High Court in Achurch v The Queen , quoting Smith v New South Wales Bar Association:
“It has long been the common law that a court may review, correct or alter its judgment at any time until its order has been perfected” 
Although it has been pointed out in Norman v Norman (1992) 6 WAR 372 at 375 that the precise time when an order or judgment is perfected is not entirely clear.
An order is considered made under r 1605 once it is either formally recorded (in chambers or otherwise) or upon pronouncement (as soon as it is spoken by the judicial officer). In an ex tempore decision the formalisation of the order is left to the associate or registry. Keeping in mind that Judges or Magistrates may not always have a chance to confer prior to or after the making of the order, it is understandable that the recording of the order, or even the reasons, can be mis-recorded to an extent that ambiguity or error exists.
The decision in Brennard examined an order made by Master Harper ruling that “The statement of claim filed by the plaintiffs on 7 September 2012 be struck out.” despite being filed on a separate date and the resulting order for costs incorrectly awarded to the plaintiff instead of the defendants as clearly intended.
Refshauge J concluded that the error was obvious and the defendants were entitled to the usual presumption of costs following the event, but questioned what to actually do about it. Having reviewed the transcript and helped by the fact the application was not opposed the Court found that as the order had been clearly expressed in court (therefore: made) it was amenable to apply the slip rule to correct the official orders as they were recorded.
There are other interesting applications of the rule particularly in relation to Bankruptcy proceedings, noting that bankruptcy rules are considered a harsh mistress to be applied even in situations that may not seem reasonable or fair. See for example Flint v Richard Busuttil for applying the slip rule to retrospectively extend the time for compliance with a creditors petition or Soil and Contracting Pty Ltd v Boban from W.A. for the equivalent in winding up applications.
If you require an order remade it is a simple enough process. An email to the Registry cc’ing in all parties, outlining the mistake and the proposed corrected version should be enough. Other parties will have a chance to comment this way and the registry can check the record or simply check with the judicial officer. The order can then be made in chambers, or if absolutely necessary listed at the officer’s convenience.