The Bhagavad Gita itself has 18 chapters with 700 verses. The context in which Arjuna says, I see such and such person, he names them. So it's a huge army of hundreds of thousands of people. And remember, all of this is being reported by Sanjay to Dritarashtra, live.
Swami Sarvapriyananda summarizes the first chapter of the Bhagavad Gita. This series of talks unfolds the highest truths of Vedanta through the study of "The song of God".