It’s a bit big, so I didn’t embed it. According to Jisho “kae” is “to return”. I got confused because it is used correctly in a sentence deck, but I kept getting it wrong – today I got them both in the same sitting.
This is where kanji (and context) becomes important. Namely, 変える means “to change”, 帰る means “to return [home]“, and 返る means “to go back [to a place]“. All are read as かえる. While we’re at it, 替える means “to exchange”, 蛙 means “frog”, and 買える is a conjugation of 買う and means “able to buy”. Not an error, just a misunderstanding due to insufficient information.
There also is one where the kana says “otoutosan” but the solution and the audio say father (otousan)
That sounds like it might just be a typo. 弟さん (おとうとさん) means “[someone else's] little brother”, while お父さん (おとうさん) means “father”.