In the Book In the Movie

Jem and Scout do not see Mr. Nathan Radely cement up the old tree. They do see him do it.

Mrs. Dubois is adicted to opiates, and while she recovers, Jem goes to her house to read to her. This is left out.

After losing his pants, Jem waits until later that night to return to the Radley house to get them. He goes back right after he loses them.

When Jem and Scout are in the Radley yard, Mr. Radley comes out with his shotgun to scare them off. He comes out later when Jem returns to retrieve his lost pants.