The actor that plays "War" is the same actor that plays Cronus in season 5, episodes "Oh my Goddess!"
Each of the 4 horsemen have a different color tie:
Green - Strife
Red - War
Yellow - Famine
Black - Death
When discussing how to vanquish a type of demon, Phoebe says that the chant is in iambic pentameter, which is ten syllables per line with the stress on the even-numbered syllables. When she later recites the spell, the spell is in the correct meter, including the stress being on the correct syllables.
Jeff Ricketts (Famine) & Brian Thompson (War) both appeared on "Buffy, the Vampire Slayer but in different seasons. Thompson was a vampire in season one of " BtVS" and Ricketts as a Watcher in season three.