TV-Nihon

i'm just wondering about the henshin noise the subtitles say: que bom but i sometimes here que bon. i'm wondering if that was a typo, a speech goof, or is my hearing nuts

It's not just you, it's a quirk of Japanese that there is no standalone m sound but there is a standalone n sound, which is frequently used to represent m sounds in foreign loan words and also can be changed to m if followed by a lip smacking p or b etc

It's just linguistics. This is why the Japanese "bon" can represent "bon dancing". "bomb dancing". or "que bom" even though it's pronounced "que bon".

As far as I know, the Portuguese "bom" sounds the same as French "bon"; that is- it can end with "ン" naturally.