This is the only known "Pink Panther" film not to feature Inspector Jacques Clouseau. Although he does appear in photographs featuring the late Peter Sellers.
When Dreyfuss discovers he is standing in shallow water, his clothes are wet and become partially see-through. Because of this, it's obvious he is wearing a wetsuit under his clothes. It's the same kind of scuba suit used earlier in the film.
Commissioner Dreyfus' non-recognition of Maria Gambrelli during the encounter at the Gambrelli home. Dreyfus considered Gambrelli a prime murder suspect in A Shot in the Dark, but she looks different (in fact, this is probably a joke on the fact she's played by a different actress).
Police Commisioner Charles Dreyfus: [to Maria]
I knew a man named Jacques. When he died, ten years ago, I thought "Thank God!" I never thought another one like him could exist... and then I met your son.