A lot of the external conflict arises from the situations that the characters find themselves in, and from the main bully of the story, Raghu. At the beginning of the story, the children are bored and clamoring for something to do, so the parents let them outside. At this point, we are introduced to some of Raghu's "techniques". He chases one kid "with such a bloodcurdling yell" that the victim starts crying. Raghu is then seen "superciliously kicking him with his toe" and finding great "satisfaction" in it. He walks around "whistling spiritedly so that the hiders should hear and tremble." So, a lot of conflict comes from Raghu's bully status: who wants to be found by him? Fear is inspired in all of the children, which prompts further hiding and furtiveness on the part of Ravi.
The other external conflicts come when Ravi needs to find a place. He realizes that next to the garage isn't good enough, so goes into it, overcoming his fear of bugs to do so. Then, at the end, when he realizes that he was late, the time factor becomes a conflict because it forces him to realize that the children didn't care about him.
Internally, the conflict arises from Ravi's desire for recognition and triumph. He wants to be rewarded and seen as neat and cool amongst his friends. He wants to win. And, because of his daydreaming in regards to this internal desire of his, he stays too long, and loses his chance. The major internal conflict, stemming from that desire, comes when he realizes that actually, the opposite is true. He realizes, with devastating force, "the ignominy of being forgotten," and by the "terrible sense of his insignificance." He is conflicted--he wants recognition, and realizes that he isn't going to get it. He's just another person, to be forgotten as time moves on.
I hope that those thoughts helped a bit; good luck!