A Fire and Emergency New Zealand spokeswoman said crews were called to reports of a small explosion and smoke inside Reading Cinema in the Octagon about 2.55pm.
Four crews were sent.
When they arrived they found a small battery had exploded but there was no fire.
An ambulance had been called and crews were leaving, the spokeswoman said.
A witness said the incident happened near the toilets about 3pm.
The man had burns to his leg and said the vape in his pocket had exploded.