I was talking to my mom, and then I realized we had been talking right into the next day.
We started talking late at night and our conversation ran into the next day.
ーI was talking to my mom, and then I realized we had been talking right into the next day.
「母と話していて、気がついたら日をまたいで話していた」
to talk right into the next day で「日をまたいで話す」
ーWe started talking late at night and our conversation ran into the next day.
「夜遅くに話し始め、会話は日をまたいだ」
to run into the next day で「日をまたぐ」
ご参考まで！
カナダ 
