When Travis comes out of the school toward the beginning of the movie, and talks to the coach, there is fog all in the background around the bleachers.
This goes from foggy, to clear to foggy, in between shots.
When Travis cuts the grass the mower is in the front yard, and he walks up to the door. But when they come out and around the side of the house, the mower has moved to the back side yard and changed positions.
When Travis is looking over the failed paper and his mom comes in with groceries, the clip holding her ID badge is on the right side of her collar in the long shots, switches to the left side in the close ups, then BACK to the right side when they zoom out again.
Part of Ely's preparation of Danny before the funeral includes adding cosmetics and presumably embalming. During a Jewish funeral, there is a closed casket, which is customary, but it would not have been okay for Ely to add makeup or embalm Danny.
When Travis says he is done with the lawn as camera follows down the yard you can clearly see the lawn is full of leaves. Even if the setting was too high the mower would have displaced or mulched the leaves.
At 1:27:50... As to survivors walk off, you can see the shadow of the camera following them briefly.