Before she is sent to the Capitol to fight in the games, Katniss is visited by several of her loved ones. Gale, her mother and her younger sister come say good-bye to her. But, surprisingly, Peeta's father comes to visit as well and offers Katniss cookies. Although the local baker doesn't know Katniss well, he has always been kind to both her and her younger sibling, and this visit helps establish the connection between Peeta's family and Katniss. Later on - in a spout of possible paranoia - Katniss throws away the cookies.
The film doesn't include these scenes at all. Most readers might not care about this exclusion but it stood out to me because these short sequences show a connection between Peeta's family and Katniss. Although the two don't know each other well, Peeta's father supported both Katniss and her younger sister by buying fresh meat and food from them. Plus, Peeta's parents have spoken to Peeta about Katniss - as Peeta notes in the story - even though Peeta and Katniss were never close.