if you look here there is a wa and a wo, as usual, and also a wi and a we. I would assume these are old hiragana that are no longer used? Anything beyond this? Would love to know just for the sake of knowing!
This is the result of what can be called "streamlining" in the Japanese phonetic system over history. The sounds "wi" and "we" did exist in the ancient days but had been replaced by the simpler "i" and "e" sounds.
I have heard professional narrators read old Japanese texts, pronouncing the sounds as they would have been read in the past, and certainly could hear them. The Japanese language has come a long way!