An 18-year-old student filming for a college project sparked a massive police hunt after members of the public reported a man carrying a sword.
Norfolk Police deployed firearms officers, police dogs and a police helicopter to Mousehold Heath in Norwich around 6pm on Wednesday night following the reports.
But the teams were stood down after the suspect's mother rang Norfolk Police to tell them the weapon was in fact a fake machete and that he was filming for a college project.
Superintendent Stuart Gunn said: "Strong words of advice were given by police to the 18-year-old male with regards to the alarm that had been caused.
"We would kindly ask members of the public if they are planning any sort of activity or filming in a public place that may prompt concern amongst the public and, consequently, trigger any police activity, to call us in advance so that we can give suitable advice.
"If the police receive reports of what is believed to be a weapon, openly displayed in public places or used in an inappropriate manner then we need to react promptly to the information that we are given at the time."