Good guess Mike, but the lab assistant in Chapters 1-3 is NOT Edwin Luke. The part of Kichi, the lab assistant to Benson Fong's character, is played by actor Leon Lontoc.
Please remember that Keye Luke was a prominent actor at Universal in 1945. He had played Kato in two Green Hornet serials in the early 1940s. Attention should not be taken away from Mr. Luke, even by his brother. Most likely Edwin Luke/Eddie Luke is an extra in the background during some crowd scenes. All actors with spoken lines are credited at the IMDb website.
In Chapter One, look very carefully at the Asian actors in the background during the fight scene inside the House of Shadows. Look at the Asian actor standing behind Nabura. He is there during the medium shots, but is missing during the wide shots. This may be Edwin Luke/Eddie Luke.
Also, look at the Asian actors playing the Japanese soldiers in the submarine.
Most importantly, listen to the voices of the actors. Please remember that Edwin Luke played a young son of Charlie Chan. His voice was youthful.
I did like seeing that Keye Luke had a brother to lend a hand to pop in the series. It would have been nice to have seen Edwin also do something with Warner Oland, but that didn't come about.