These Sidney Toler "Monogram" Chan films, the last in the series, don't measure up to Warner Oland's earlier efforts but they are still very entertaining to me. Even with Mantan Moreland, who probably offends the sensibilities of a lot of people with his scared black-man routine. I can see where that's offensive, but if you just take him as a comedian and let it go, you can enjoy and even laugh with him.
The only thing I did NOT find funny in here, but I normally do, is Charlie's insults to his kid. In this film, Tolder insults "Number Three Son" (Benson Fong) so many times that it borders on downright mean-spiritedness.
Anyway, it was still a "decent" combination of mystery and comedy and the ending was cool, with Chan and his assistants chasing the bad guys around a "fun house." All the Charlie Chan movies are entertaining.