Speaking to NBC on Wednesday, Ms Neas said she and her son were told about the accident by ground staff at the airport in Melbourne.
“They said, ‘Look, we’ve found your cat, but it’s actually on a return flight to Christchurch…’
“And I said, ‘When did you find out the cat wasn’t taken off the plane?’ And they said, “We just opened.” And I said, “How can that happen?”
Ms Neas said she was told the pilot had already been warned to turn on the heating in the cargo hold, where temperatures could drop to 7C.
The incident is still under investigation, but reports say the wheelchair that was put down may have blocked a baggage handler’s view of Mittens’ cage.
Air New Zealand apologized for the disaster, promising to reimburse all travel expenses.
The company does not accept direct bookings for pets on international flights from the public, so passengers must book through approved pet carriers.
Ms Neas said she was relieved to finally be reunited with Mitten.
“She just ran into my arms and snuggled up here and gave me the biggest hug of all time,” she was quoted as saying by the AP agency on Wednesday. “It was just such a relief.”
Ms Neas, who had previously decided to move to Australia, added: “It wasn’t a good start to our new life in Melbourne because we didn’t have a family, we weren’t complete.”
A one-way flight between Christchurch and Melbourne usually takes less than four hours.