Goofs

When the spacecraft nears the moon and the Third Echelon controller tries to avoid their crashing into the lunar surface, the controller turns the steering wheel to the right. However, the spacecraft is shown turning to the left.

As Harry and Chester attempt escape from the 3rd Echelon's Control Room, the leader has moved from the middle of the floor to being comfortably seated at a desk almost instantaneously.

As Chester Babcock is lifting off in his flying suit, the propeller behind him has stopped moving, but in the next shot a second later he is ascending and the propeller is spinning again.

When Chester and Harry look out the porthole of the underground base, they discover they're under the ocean. Fish are seen swimming just a few feet beneath the calm surface water of a tank, not the agitated surface water of an ocean. When they see a shark a moment later, no water surface can be seen. It's also a traveling shot, with the camera following the shark's progress, suggesting that the stationary underground base is swerving to observe it, which it can't.

The criminal wanted flier on Chester and Harry lists Chester's birth date as May 3, 1921, and his age as 39. The flier is dated May 18, 1961 - half a month past Chester's birthday - which would make his age 40, not 39.

Soon after the rocket is launched, Dr. Zorbb announces that it is at an altitude of 120 miles, and has escaped the Earth's gravitational pull. That is a common misconception. Actually, at that altitude, Earth's gravity is still 94% of that at the surface. (Weightlessness in orbit is due to an orbit being the equivalent of a free fall.)

The wanted flier on Chester and Harry lists Harry's eye color as brown. The Road to Honk Kong (in black and white) follows The Road to Bali (in color) where Harry's blue eyes (Bing Crosby's natural color) may have been noticed.

When Harry and Chester jump to stamp on the henchmen's feet, they visibly actually do not land on anyone's feet. Furthermore, the henchman on the far right takes a step backwards at the last second to protect his feet, knowing what is about to happen.

Harry loads Chester's shirt with a couple dozen live fish, but as they turn and run, Chester's shirt is neither bulky, squirming nor wet.

Every time that Chester brings reciting the last two lines of the rocket fuel formula, it is entirely different from the time before.

As Chester, Harry and Diane escape the secret base, they drive down a cliffside roadway overlooking (presumably) one of the bays of Hong Kong. As absolutely nothing is moving in the bay, it is obviously a painting. Looking carefully at the roadway barrier wall, a line where the side meets the top can be seen shifting about slightly due to the camera filming the car chase not able to remain absolutely still.

In the opening musical sequence, title cards for the previous "Road" movies appear, but all are incorrect in that they prepend "The" to the title. Only this movie actually has "The" at the beginning of the title.

Visiting a Tibetan monastery in 1962 would have been utterly impossible. Following the 1959 Tibetan revolt, Mao's Great Leap forward had the monasteries forcibly closed at the cost of up to 200,000 Tibetan lives and utterly isolated the entire country.

The Buick in the opening scene has a license plate the reads "Empire State," the nickname of New York.

As Chester Babcock is lifting off in his flying suit, the propeller behind him has stopped moving as the motor driving it has clearly stopped, yet the sound effect is of a small motor revving up.

As Harry and Chester are going into the basement of the head spy, Chester's hat is lifted off his head by a very visible wire.

Neither Chester nor Diane ever give the hotel's name. There is no explanation how she could have found their hotel after their return from Tibet.

Chester, Harry and Diane escape the secret base by submarine. Instead of going anywhere else as all, they only use it to escape back to the estate atop the secret base, where their pursuers, having merely taken an elevator, end up close behind them.