In their haste to get away, they lost control of the vehicle and crashed into the power pole.
The man had blood on his face as a result of the assault and not the crash, Senior Sergeant Bond said.
Investigations were ongoing into the incident.
On Sunday, in an unrelated incident, police stopped a vehicle travelling in George St at 11.15pm and talked to an 18-year-old driver.
While police were speaking to him and he was searching for his licence, officers spotted a bag of cannabis sitting in the centre console of the car.
Officers invoked a warrantless search and located 28.35g of cannabis and $2000 in cash.
He was charged with possession of a pipe and utensils for cannabis and for supply of cannabis.
He will appear in the Dunedin District Court tomorrow.
laine.priestley@odt.co.nz