Interesting read - thanks for sharing!
I think it's particularly noteworthy that the Court refers to section 90 of the Provincial Offences Act for its decision:
"Irregularities in form
90. (1) The validity of any proceeding is not affected by,
(a) any irregularity or defect in the substance or form of the summons, warrant, offence notice, parking infraction notice, undertaking to appear or recognizance; or
(b) any variance between the charge set out in the summons, warrant, parking infraction notice, offence notice, undertaking to appear or recognizance and the charge set out in the information or certificate.
Adjournment to meet irregularities (2) Where it appears to the court that the defendant has been misled by any irregularity, defect or variance mentioned in subsection (1), the court may adjourn the hearing and may make such order as the court considers appropriate, including an order under section 60 for the payment of costs. R.S.O. 1990, c. P.33, s. 90."
Section 90(1)(a) seems to address any errors (or irregularities or defects) on a ticket. The Court, in its decision, said that errors such as incorrect name, incorrect municipality, etc. is not enough for a justice to invalidate a proceeding.
Section 90(1)(b) seems to address any errors corrected by a police officer (variance between the offence notice and the certificate). The Court, in its decision, said that the Act does not explicitly say that the police officer can or cannot fix errors, but section 90(1)(b) would lend itself towards justifying any errors corrected.
And finally, section 90(2) provides for a remedy if the error causes the defendant to be misled or prejudiced. The Court gave the example of a police officer completely changing the charge on his copy of the ticket after already giving the ticket to the defendant, since this would affect the ability of the defendant to provide full answer and make a defence.