YOU SAID:

I had mustard in the nose when I saw them buying with their eyes.

INTO JAPANESE

私は彼らが彼らの目で買っているのを見たとき、私は鼻にマスタードを持っていました。

BACK INTO ENGLISH

I had mustard on my nose when I saw them buying with their eyes.

INTO JAPANESE

私は彼らが彼らの目で買っているのを見たとき、私は私の鼻にマスタードを持っていました。

BACK INTO ENGLISH

I had mustard on my nose when I saw they were buying with their eyes.

INTO JAPANESE

私は彼らが彼らの目で買っているのを見たとき、私は私の鼻にマスタードを持っていました。

BACK INTO ENGLISH

I had mustard on my nose when I saw they were buying with their eyes.