One woman was told it would take place from 7pm.
A fake website advertising a Halloween parade in Dublin city centre tricked thousands of people into turning up last night.
Gardaí had to ask people to move on after they lined O'Connell Street in anticipation of the event.
The website had promised a parade running from Parnell Square to Temple Bar.
This woman was told it would take place from 7 to 9 o'clock:

GRA Meeting Tomorrow To Decide If Gardaí Will Take Industrial Action
Belfast High Court Upholds Ban On Drumcree Orange Order Parade
Major DART+ West Works To Begin This Weekend As Plans To Extend Electric Rail Services To Kilcock Progress
Court To Rule On NI Secretary's Decision To Ban Drumcree March
Justice Minister To Meet Law Society Amid Ongoing Legal Aid Dispute
High Court Judge Overturns Initial Refusal Of Study Visa For Palestinian Student
Gardaí Continue To Investigate Death Of Woman In Finglas
Wholesale Electricity Prices 93% Higher Than Last Year