Bob Fleming wrote on the Facebook page of Taranaki Daily News to say "something from the fireworks" hit her daughter's arm.
"She said it felt hard and hot - and stung," Fleming wrote.
"Fright factor mainly but still a bad event to a great night."
Amy Shotter wrote that "a big chunk of something hit us from the fireworks".
Another poster said a small piece of fireworks debris hit her eye.
Event organiser, Michael Keat of New Plymouth company TLL events, said he was aware of one fireworks that strayed towards the crowd.
However, he was not aware of any injuries.
No-one has contacted his company to say they had been hit by debris.
"We've seen it on Facebook [but] nobody has officially reported it to us," Keat said.
"We're aware a little bit of rubbish came down but the fireworks was done no differently to how it's been done in previous years.
"There was only one firework that went that way [towards the crowd] and we don't know why it did.
"They comply with all the rules and regulations required. You have no control over fireworks, as you are well aware from the manufacturer.
He added: "Anything that is likely to have fallen on them is likely very small and wouldn't have harmed them in any way."
Keat said it was a "brilliant" event but he urged people to get in touch if they had any safety worries.
"Obviously the solution to it, if people have concerns, is that we stop the fireworks."
