The show's premise was a combination of soft science fiction and ideological fantasy. In each episode, Dr Sam Beckett 'leaps' into a person (oddly enough, usually an American) living sometime between 1950 and 1990 (although the show was theoretically set in 1999, since it was filmed in the late '80s and early '90s, he never leaped into anyone from the 1990s). Taking the other person's place, he 'sets right what once went wrong', repairing relationships, solving mysteries, saving orphanages and that sort of thing, often saving the leapee or someone close to them from death by crime/accident/wrongful execution/illness that he can cure with his 1990s knowledge of medicine.
This episode plays with the themes of mummy movies, as Sam leaps into an archaeologist who disappeared, together with everyone else with him, while excavating the tomb of King Ptah-Hotep II (not, as far as I know, a real Egyptian king, but it is a real Egyptian name, deriving from the god Ptah and 'hotep', often used as a suffix in Egyptian names and meaning, in context, 'Ptah is content'). This gives the writers a chance to play with some tropes that aren't usually part of their toolkit.
Usually, the only science fiction/fantasy element of the show was the leaping itself. As the series went on, and particularly in Season 5, other elements started to creep in (a possible vampire, aliens, a leap outside Sam's lifetime that wan't ususally possible according to the show's internal logic, and most notably an opposite 'evil' leaper). This episode appeared late in Season 4, before the vampires and aliens, but after an early episode playing with horror themes and the works of Stephen King ('The Boogieman') and more particularly, after 'It's a Wonderful Leap', which featured an actual angel. The great thing about this is that the audience isn't quite sure what to expect. Al suggests that the mysterious deaths that start to occur are murders, carried out by someone who's after the treasure for themselves, and that would be the sort of solution you would anticipate from Quantum Leap at this point. However, there's just enough doubt in the audience's minds to add a really nice layer to the mystery - not only, who is doing the killing, but is it a living human being at all?!
In the end, it turns out that there is a murder plot, of sorts - but there is also a mummy, and we see his hand, though thankfully not any more of him. I'm never quite sure how I feel about Quantum Leap doing these more overtly fantasy/science fiction stories, as it doesn't quite fit the tone of most of the show, but on the other hand, it does provide a nice change of pace and it wouldn't be a proper mummy movie without an actual mummy.
Another nice thing about this episode is we get to see a bit more of Sam as a character, in a way that isn't always possible. A while back, I wrote about how TV and film archaeologists are always ridiculously over-qualified and somehow manage to be experts in just about everything, never restricted to their own field like normal people. Well, Dr Sam Beckett really takes the biscuit here. He ought to be Dr.Dr.Dr.Dr.Dr.Dr.Dr. Beckett, at least, as he has seven degrees that come with the title 'Dr' (six PhDs and an MD), though his qualifications, along with his life story, can be changed sometimes if he affects his own past while leaping. It was established way back in Season 1 that one of his PhDs was 'Ancient Languages', including ancient Egyptian (an unusual subject - Classics, Egyptology or Ancient History would be more normal - but plausible. Ish.) and apparently it still is, as he can still read hieroglyphics. He also gets very excited about being in Egypt, about working with fellow archaeologist Ginny - with whom, refreshingly, he develops no romantic attachement and has an entirely professional relationship, despite the tiny tiny shorts she's wearing - and about their discovery, because he's genuinely interested in Egyptology and ancient history. It's fun to see Sam enjoying one of his own areas, rather than having to throw himself into someone else's, and of course it means the episode avoids the usual issues of how he can fit in and convince people there's nothing wrong with him, as he knows what he's talking about.
An episode with a mummy in it can't take itself too seriously, and there are some great moments of humour in here (like Al's assessement of a camel as an ugly horse - he's quite wrong of course, camels are beautiful). Other attempts work a bit less well; Ginny notes that claustrophobia is 'hardly a good trait for an archaeologist', but most archaeologists don't work in tiny underground tombs, they work in the open air! (Though some work in cellars and trenches, which looks even more claustrophobic). If she'd said 'Egyptologist', which is what her character actually is, that could have worked.
This isn't one of Quantum Leap's finest hours - the best episodes of Quantum Leap tend to be those which deal with serious subject matter in a dramatic way, or the romantic episodes, or those which are really broad comedy and involve Sam wearing women's clothing. It is also indicative of the slide into more and more 'out there' episodes in Season 5 that would culminate in the show finishing at the end of that season. It's good fun though, and it's nice to see that old Ancient Languages PhD brought out again - even I have to admit, that's not one that he needs to use terribly often in the course of leaping.