Parts of the town were turned into an American town as the 40-strong Queenstown-based film crew spent the day filming a commercial for a United States blood-thinning medication.
Location manager Cameron Wood said he was delighted with the reaction of residents and businesses.
"The energy here has been really great."
He also praised the co-operation from business-owners.
The House of Travel was used as a set to film an internal location, he said.
Ambience Hair Design was "completely stripped out" and transformed into a United States florist shop for the day, complete with US Mail boxes on the pavement and the Stars and Stripes draped from the veranda.
Oamaru residents are fast becoming used to appearing on TV and cinema screens.
Bianca Bogan, from Waitaki Valley, said she jumped at the chance to appear on-screen, as an extra, for the fourth time.
"I heard from a friend that they were looking for 15 locals to appear as extras, so I just rang up and took it from there," she said.
She had already appeared in one other commercial filmed in Oamaru, as well as the recent Mr Pip movie, which was also filmed partly in the town, she said.
"I also had a role in The Lion, the Witch and the Wardrobe, as an extra, when that was filmed at Castle Hill."
