I've already seen it once, and due to an awkward lab schedule, I was running on next to no sleep. Nonetheless, when this movie played in class, I was so into it I forgot to pay attention to the filmmaking.
Murderball taught me to make characters react differently to different things - scary, intimidating Zupan is a touching father figure to Keith. The events of any story are exactly as meaningful as the characters believe they are. Audiences take our cues from the characters. If one guy is blasé about losing his legs, losing your legs must not be that big of a deal. But if another guy almost breaks down under the strain of trying to cope with it, then the first guy's a tough guy and accidents suck.
Murderball also taught me that brief animation sequences can be awesome. They can help explain abstract concepts, or provide a visual element to, say, a monologue.