Did you know that the monkey on Arjuna's flag doesn't have a name, almost every time he is mentioned?
As far as I'm aware, the only time the monkey is identified as Hanūmat is Āraṇyakaparvan 150.15, where Hanūmat says to Bhīma, "Positioned on Vijaya's flag, I'll emit terrifying sounds that deprive your enemies of breath!" (Vijayasya dhvajasthaś ca nādān mokṣyāmi dāruṇān śatrūṇāṃ te prāṇaharān). This incident of Bhīma meeting Hanūmat may have been added to the text rather lately, as there are two versions of how Kṛṣṇā Draupadī sent Bhīma on a quest to Kubera's pond after finding a divine flower (Āraṇyakaparvan chapters 146-153 and chapters 157-159).
Otherwise, in all of Arjuna's battles, his emblem is just a nameless monkey.
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