YOU SAID:

I went to the store and the carts were full of mini people

INTO JAPANESE

私は店に行って、カートはミニ人でいっぱいでした

BACK INTO ENGLISH

I went to the store and the cart was full of mini people

INTO JAPANESE

店に行ったらカートはミニ人でいっぱい

BACK INTO ENGLISH

When I went to the store, the cart was full of mini people

INTO JAPANESE

店に行ったとき、カートはミニ人でいっぱいでした

BACK INTO ENGLISH

When I went to the store, the cart was full of mini people