The first complication Rainsford faces is the sea. After falling off the boat, he must fight the sea to survive. That, however, was far from his biggest complication. Although appearing civilized, General Zaroff is everything but civilized. Rainsford discovers (to his horror)that Zaroff hunts other MEN, not animals. Because Zaroff gives him no other choice, Rainsford must evade Zaroff for 3 days as he hunts him down.
So Rainsford's first complication with Zaroff is successfully hiding from him in the jungle. Although he feels he was able to keep hidden, he finds that Zaroff is only playing with him and chooses not to capture him on the first day. Next, Rainsford places traps out for Zaroff, and they do not pan out for him either, as one of the dogs sets off his first trap, and Ivan is taken out in his second trap. Rainsford does slightly injure Zaroff's shoulder, but it is not life threatening. His final complication is making it back to the chateau without being caught and then facing Zaroff for the final battle.
Many obstacles were in his way, yet he was able to maneuver his way through them and succeed in the end.