While we're on the sidebar of illogical sequel titles, I Still Know What You Did Last Summer is a notoriously dumb one, given that its events take place a year after those depicted in I Know What You Did Last Summer.

Or we can talk Son of Dracula in which at no point is it ever suggested that the villain is the son of Dracula. He's just Lon Chaney Jr. playing Dracula.

Still, each of these are sequels to a franchise, regardless of who the titles are referring to.

Lester directed an adaptation of that, with most of the cast back, as Return of the Musketeers; but, sadly, Roy Kinnear (Planchet) fell from a horse and was killed, during filming.  It does seem to cast a pall over the sequences that were obviously done later.  It messes around a bit with The Twenty Years After, though not as badly as most versions of The Man in the Iron Mask.

Dumas actually wrote those as serials (same with Count of Monte Cristo), first, which is why they seem so episodic, for novels.  The next sequel is technically The Vicomte de Bragalonne; but, that usually gets split into three parts: The Vicomte de Bragalonne, Louise de Lavallier and The Man in the Iron Mask.  In some editions, Vicomte de Bragalonne gets split into two segments, with that title for the first and The Ten Years Later, as part 2.

Along similar lines, there are film sequels to The Count of Monte Cristo, with Son of Monte Cristo and Return of Monte Cristo.  Roland Lee directed the first two, in 1934 and 1940, respectively, then Henry Levin directed Return, in 1946.  All three were produced by Edward Small.  Robert Donat is Dantes in the first and Louis Hayward stars as descendants of the original count, in each (different ones).  Son of is pretty much a swipe of Prisoner of Zenda, with some Zorro touches thrown in.  Return has a descendant imprisoned on devil's Island, plotting to escape.

A Shot in the Dark features a different naming convention mostly because it was an adaptation of a stage play by Harry Kurnitz (based on Marcel Achard's L'Idiote), in which Clouseau was inserted, rather than an original Clouseau script.  The title is the title of Kurnitz's play.  Sellers had been signed to star in an adaptation, but didn't like the script (this was even before the release of The Pink Panther).  Walter Mirisch approached Blake Edwards about taking it over; but, he was reluctant to do so, until they allowed him to insert Clouseau into the story.

There is another non-Pink Panther  film, featuring Clouseau, called Inspector Clouseau, with Alan Arkin.  Sellers, Edwards and Henry Mancini were all busy with The Party; but, Walter Mirisch wanted to proceed with another Clouseau film and hired Bud Yorkin to direct and Arkin to star.  It's nowhere near as good as Edwards films, but it isn't bad.  More amusing, at times, than hilariously funny.  Still better than those later Pink Panther films, following Revenge of the Pink Panther.

Funny enough, A Shot in the Dark is the one that introduces Cato and Chief Inspector Dreyfuss to the series.

Don't forget the Gamera film, Destroy All Planets!

Getting back to the Planet of the Apes, I loved the titles they gave to the movie edits of the tv series episodes:

Back to the Planet of the Apes
Forgotten City of the Planet of the Apes
Treachery and Greed on the Planet of the Apes
Life, Liberty and Pursuit on the Planet of the Apes (my favorite of the bunch, title-wise)
Farewell to the Planet of the Apes