At the beginning of season 2 of Doctor Who (2005), I noticed Rose Tyler changes clothes after she gets possessed by Cassandra. First she's wearing a blue top, then it's short-sleeved and purple for the rest of the episode. Is this explained?
She takes her cardi off, the other top was under it from the start, so might not need that much explanation. This is shortly after she (Cassandra) comments 'nice rear bumper' so presumably is trying to show off a bit more cleavage to take advantage of her host's charms. Also IIRC Cassandra gets a bit hot sometimes - Chip's heart starts racing and he just ups and dies shortly after she transfers to him.
(out of universe I suspect it was the other way round, she wore extra clothes in the scene where she got soaked, it's a kids' show after all)