Plot hole: Series 2: In the episode where Yolei and Sora go to Russia, they can't talk to the Russian kids, because they can't speak Russian. However, the Russian digimons speak English and they surely speak Russian, so Yolei could just have asked them to translate what she was saying.
Other mistake: The DigiDestined refer to Arukenimon by name before she formally introduces herself. Before her introduction, it is not established that the strange woman is in fact a Digimon.
Other mistake: When Veemon, Armadimon and Hawkmon are about to rush in and save Gatomon, a previous frame of Hawkmon's beak stays on-screen. (00:16:15)
Answer: Digimon started as a series of virtual pets, making them digital. In the television series, Digimon live in the "digital world."
Bishop73