Are we all forgetting that Zetsu is his "eye and ears" and he can even record everything he/it sees. Plus this chapter gave a solid evidence that Madara and Zetsu are linked mentally (since it is his will after all), so it's easy for him to catch up. He was also talking to Kabuto the whole time, who used to be a spy who holds information about everything and worked under someone who had a deeper obsession with gathering information. Madara's well schooled.
Now, imagine having the "review" (if that was even necessary for him to get those info from his own Will) while fighting in the war and the present day Gokage. That's total toying and amusement.