There's no other explanation. You see his teammate on the right of the screen takeoff down court after the rebound. It was just a really really bad pass.

Edit: watching it a few more times I'm less certain, but judging by his reaction he definitely didn't think he just hit a game winner or anything.

Edit 2: why did no one at all react. Every single person in this video just shrugs and keeps playing. This is such a mystery.