Ian Lindsey’s review published on Letterboxd:
This is the most continuity that I've yet seen out of the classic Universal sequels. This also takes things in a much grimmer direction than Hand, jettisoning the slapstick elements, running right over the relatively happy ending, and unceremoniously killing off the aging protagonists of that movie.
Chaney (credited without the Jr. here) makes for a great mummy. He's pretty banged up after being set on fire at the end of Hand and is now a one eyed murder machine. He also gets way more screen time as the monster than the first two movies offered.
But man is there a lot of recycling. Footage from the last two movies in the series and the original Frankenstein all make an appearance. The movie even starts with a ten minute recap of Hand which in a movie that barely cracks an hour feels like a bit much. The ending also takes some cues from the original Frankenstein.
Watching all of these is making me want to revisit the Hammer Mummy that turned this franchise into a British flavored greatest hits medley.