老實講 lo5 saat6 gong2 - to tell the truth
如果我無錯嘅話 yuu4 go2 ngo5 mo5 gong2 co3 ge3 waa6 - if I'm not mistaken
總之 zong2 ji1 - Anyway (lots of people just say Anyway in English lol)
問得好 mun6 daak1 ho2 - that is a good question

As a recommendation, I'd stay away from Google translate for language learning - translate is smart, but not smart enough to beat a native speaker (yet - maybe in another 10 - 20 years? lol). It's best to consult a dictionary, but for Cantonese, since there aren't any "official" dictionaries, a consult with a native speaker can always confirm what you're thinking. 

Good luck. 

上面幾位嘅回答好標準

我自己係講粵語嘅,唔係專業人士,只是母語使用者.

我補充嘅係日常口頭表達,僅供參考,唔知你用唔用得上,亦都歡迎各位指出我嘅錯誤 :-)

to tell the truth - 講真

if I'm not mistaken - 我無搞錯嘅話

Anyway - 總之/點都好

that is a good question - 問得好

to tell the truth - 講真話

if I'm not mistaken - 如果我冇錯既話

Anyway - 總之

That is a good question - 問得好 OR 呢個係一個好問題

hhh ok sure, I was wondering what is easiest to translate 

to tell the truth - 說實話 

if I'm not mistaken - 如果我沒算錯的話

Anyway - 那麼

That is a good question - 問得好

Did Google give Chinese characters with the translations? It would be easier to give an answer.

the last for that is a good question looks ok