In the episode "A New Hope" (01x20) there is a "Star Wars"-like introduction to the show. There are no regular opening credits, the cast member's names are played out over a scene.
In the episode "An Eric Forman Christmas" (4x12) the "That '70s Show" title is decorated with christmas tree balls. During the opening credits christmas bells can be heard.
The Halloween episode "Too Old to Trick or Treat, Too Young to Die" featured a special font for the credits, and the theme had organ music playing in the backround.
In the opening credits for the Halloween episode in 2000, the title song has creepy organ music playing along with it. Also the actors names appear in a "spooky" font.
During the opening credits of the episode where Fez dreams about the cast singing and dancing to some of the 70's most well known songs, the names of the cast members are in silver and two searchlights go across each name. Also, two searchlights go across the license plate at the end of the opening.
In the episode "Christmas" (6x07) the "That '70s Show" title is decorated with Christmas tree balls again. During the opening credits Christmas bells can be heard. This was used before in episode 4x12.
Closing credits: License plate stating "America's Dairyland Carsey-Werner Deo, Wisconsin '78"