My Grandparents, James Reilly and Annie Jane nee Prince date of marriage is 16 August 1911 not 16 November 1911 as you have recorded.
Would you please amend
Where are you seeing this?
If it's in the collaborative, shared Family Tree on FamilySearch, that's open-edit: you can make the correction yourself, by clicking the edit (pencil) button next to the incorrect marriage date.
If the error is in an indexed historical record, then it depends on the specifics whether you can fix it or not, but either way, the index has served its purpose perfectly: you found the record.
Barry if you have the original marriage certificate get it scanned and put it in the sources that way we can officially put it together and undo the incorrect marriage date. Original documents and things and statements from primary sources help put things into perspective. Primary sources are those from those people who were at the event witnessing the event. That way we can also distinguish between two people with the same name and similar dates of birth, weddings, and deaths.