An idiom that fits the scene

Scene 1

SimonTam: "Do we have to write 'of Hong Kong' time and again? Hmmmmmmm.......... 'Furthermore, parks in Hong Kong ............' it is clearly stated the parks in H.K, so we don't need to repeat that."

Ahliu: "「to write " of Hong Kong" time and again?」 hmm... Obama never said 'United States of America' in his speeches?"

GarlicdogLee: "Aliu, you are so dumb to bring up this! Obama is black! Are you? Obama is the American precident, are you? You shouldn't have compared your Chinglish with his!!!"

Ahliu: "I don't see what you mean actually. I'm not black and I'm not a president. You still fail to point out why I shouldn't mention "Hong Kong" in that article."

ShanChan: "I am neither black nor a president.(simple and clear) You failED to point out why I shouldn't have mentioned in that article again!(use proper tense) I DID NOT fail to do that! You failED to get it! That's your problem, not mine. You are not Obama, therefore you should not HAVE BROUGHT HIM UP to prove yourself right."


Is there an English idiom that describe a similar situation, sidetracking from the core of the issue by focusing on unrelated details?