Ocean Park deputy chief executive Matthew Li Sing Chung said the balloon landed on a pedestrian walkway instead of its pad because of the leakage and wind, but witnesses said the balloon hit a tree before landing near a fountain.
He said there were no announcements in the park about the accident but "we immediately notified the Electrical and Mechanical Services Department about the incident".
But Hong Kong Polytechnic University mechanical engineer Lo Kok Keung said the park is fortunate to have escaped a disaster.
"It's lucky there was still helium in the balloon,"The Standard quoted him as saying.
"If there was no helium, it would have fallen at a speed that could probably have killed everyone on board."
A detailed weekly check on the balloon on Tuesday did not show anything amiss, nor did the daily checkshow up any fault.
This article was first published in The New Paper.