In the episode, Nature Nightmare, the main villains were Rasputin Zero and his mutated trees. Rasputin Zero altered a forest to protect itself from people who wanted to destroy it. To that end, the trees attacked anyone in the forest with their vines, and put them in pods, where they would be slowly digested.
According to Zero, when Sam, Clover, and Wade were captured by the forest vines and placed in their cocoons, Zero said that it would've taken several days for them to be digested.
The only way that Zero could know that, (aside from the fact that he created the mutant forest) is if the forest had already digested a few humans. If that's the case, then does mean that, while the spies may've saved everyone, including Alex, there may've been a few people that they failed to save in time? What do you think?
(References: Totally Spies- Nature Nightmare- Wiki- Images)