One of them seemed to die in the first Beastmaster, but both were back in B2 ( both called by name ) ,they seemingly were left ? in LA in B2 but are back in B3 ( again both called by name ) . The continuity here is as bad as in the Godzilla series.
shareAlso Rue changed from a tiger in the second movie to a lion in the third. (I haven't watched it recently, but I'm guessing he is also the black tiger in the first movie since Sharok and Kodo and Podo are all the same.)
shareActually, while one of the ferrets dies at the end of BEASTMASTER, moments later we see two baby ferrets in Dar's satchel. These are likely the two grown-up ferrets we see in BEASTMASTER 2, just with the same name. I haven't seen B2 in many years so I don't recall if they were left in the present or not. If they were, it's likely Dar just had two new ones by the time of BEASTMASTER 3 and simply (again) named them Kodo and Podo, probably out of his fondness for the original two. :)
shareThis works as an explanation in-universe.
It's also true that each film had a different writer and each writer was probably either ignorant of the first film or just decided it was worth ignoring continuity in order to maintain the animal companion formula. Though to be fair, this movie does actually make sense as a sequel and involves characters from the first film, which is more than I can say about Beastmaster 2.