In the movie, Ron makes a joke with Harry about how a fat girl from whatever house she was in can't be a swan because she's fat, during a class where McGonagall was teaching and Mr Filch was figuring out how to use a Muggle technology music device.
Then he fights with Harry some way through the movie.
Offends Hermione a couple times.
And pretty much annoys the entirety of Gryffindor sometime before Harry wins the golden egg.
Why was Ron so mean to some people in Goblet of Fire?