I am not sure what "serious error" mean but you should read up on Fatal Errors ... if there is a Fatal Error on the ticket, then you should NOT got to trial (and not have anybody attend for you) and if the JP sees the error they will drop the charge. If the JP does not see the error, then you can then appeal based on fatal error and have it dropped. As long as nobody shows up for trial on your behalf, then a trial has not actually taken place and the prosecutor can NOT amend/fix the ticket. If you or paralegal go to trial and there is a fatal error on the ticket, the prosecutor can amend/fix it on the spot and then they say "thanks for pointing out our error" and then go on with trial and you get charged and you cannot appeal the fatal error anymore because they were allowed to fix it at trial. Also if they amend/fix it at trial then there is no more "officer lied on the summons issue" either (because they fixed it). And if the officer did lie on the summons and you can prove it, that is a separate charge against the officer that does not have anything to do with your charge.
I am just making assumptions here that a "serious error" is a fatal error, which of course it might not be, but either way it is usually a bad idea to point out to the prosecutor problems with their case as you have now given them a heads up to what they need to either fix or address in their case.
Can you post a copy of your Offence Notice (with license plate blacked out and officers name blacked out and your personal information blacked out)?
+++ This is not legal advice, only my opinion +++