In chapter 2, "Mechanical Executioner," when Professor Dodge agrees to talk the tractor in close-up is halfway over a partially crushed packing crate. In the next shot the crate is completely crushed under the tractor's tread.
The Mayan Treasure Map was described as being on two halves of a copper plate. But in the foreword in chapter 14 it is described as being on a bronze plaque.
Didn't carry a shield like the Captain America in the comic books.
Chapter one: You do not smell an unknown substance with your nose. You gently waft with your hand over the container, then sniff your cupped hand.
Throughout the serial, the word "Mayan" is pronounced "MAY-an" instead of the correct "MY-an."
Don't you think that Purcell, Dick is a little pudgy to be playing "Captain America?"
In chapter 11, some film equipment is reflected in the rear window of the ambulance as the bad guys get inside.
In the last chapter the clock which is shown chiming as the Scarab is executed is Big Ben (London, England) despite the serial being set in the United States.