James Gandolfini requested ice and cold water to stand in so he would really be shaking during his sick scenes.
According to Todd A. Kessler, he was summoned to David Chase's office and told he was fired the same day they both received an Emmy nomination for writing the season finale. Kessler was able to convince Chase to give him a second chance, but was subsequently let go again during production of the third season.
During the dream scene where Tony is waiting outside of Dr. Melfi's office, the painting of a barn and tree that is seen and talked about in season one can be seen on the wall. In the first season, the barn is red. In Tony's dream it is now a light grey, appearing almost colorless.
Only the second episode written by producer Todd A. Kessler, but he and co-writer David Chase earned an Emmy nomination for it.