Other mistake: When Buck tells about his fight with Rudy, he swings while saying "Back, forth" in front of the others. They are looking the wrong way. He is also swinging on nothing at all.
Ice Age: Dawn of the Dinosaurs (2009)
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Directed by: Carlos Saldanha, Mike Thurmeier
Starring: John Leguizamo, Denis Leary, Ray Romano, Eunice Cho
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Chosen answer: He failed at hunting and believes staying with the herd has damaged his predatory instincts.
BaconIsMyBFF