Crew or equipment visible
Both young men, having grown up in Wyoming, would not take such a job without a sleeping bag. If you grew up in the mountains, you would know that snow is expected every month of the year and it is not uncommon for the temperature to drop to below freezing on a regular basis. A blanker or two or even three is not enough.
When Ennis receives Jack's first postcard it's sent general delivery because Jack didn't know Ennis's address. When Ennis writes back all he says is, "You bet," and leaves no return address, thus Jack still doesn't know where he lives (just the town). In the next scene Jack arrives at Ennis's apartment without this vital information.
During the rather important kitchen sink conversations after the family holiday dinner, a props tag is plainly visible on a dish's underside. As the dish is conspicuously hand-washed under running water, the underside faces the camera and the large masking tape tag with marker lettering goes unacknowledged by the cast.
When Ennis comes back to camp late at night after he encounters the bear, Jack asks him where he's been. It's supposed to be cold but when Jack talks you can't see his breath. When Ennis tells his story about the bear, you can see his breath, but when they continue talking, neither one's breath can be seen in the cold night air.