It’s absolutely a prop, and it’s made to look like the makeshift suitcase of a travelin’ man.
He’s in his motion-capture suit, the duds that allow a mild-mannered actor to turn into the raging, green, smashworthy Hulk.
There are a number of things to unpack in this image, which Mark Ruffalo claims is from his “last day on IW,” which is this summer’s Avengers: Infinity War.
Hulk looks like he’s in an alley, surrounded by trash.