• Holiday candles (not those terrible ones still left over from Hanukkah)
  • Carafe of wine (Fine maybe not a carafe but a few bottles at the least)
  • Seder Plate
  • Cup for Elijah
  • Cup for Miriam
  • Travel sickness/barf bag for Elijah and Miriam (You would need one too if you were drinking a glass of wine at every Jewish house in the world)
  • Three Matzot
  • Afikomen Bag
  • Salt water for dipping
  • Chairs (These are pretty important the ground isn't too comfortable)
  • A Haggadah
  • Wine cup for each person
  • Matzah ball soup (Probably made by the most jewish person in attendance)
  • Gefilte fish
  • Actual meat for the meal

haggadah Section: Introduction
Source: For This We Left Egypt By: Dave Barry, Alan Zweibel, and Adam Mansbach