'Oh, for a second there I thought you were a Jap' (Spoilers)
This line, spoken by Lee Marvin, summed up for me how the relationship between the two characters had changed during the course of the movie. Plus, it is very funny, if you think about it.
Initially they were bitter enemies. By the time they reach the bombed-out base on the island, they are comrades.
(Marvin says these words while they are clambering about in the bombed-out base. He is startled by a noise, only to find it is Toshiro Mifune.)
Like a bird on the wire, like a drunk in a midnight choir, I have tried in my way to be free