This may not be 100% accurate, but I think TAR 29 is the only Season to have teams go from 1st to Worst on 3 separate occasions. (The most of any Season)
Tara & Joey - 1st Leg 8, Last Leg 9
Becca & Floyd - 1st Leg 9, Last Leg 10
Matt & Redmond - 1st Leg 10, Last Leg 11
If Brooke & Scott come in 3rd on the Final Leg, this record will increase to 4 separate times.