"The Amazing Race" federal agents' cover story challenged

(CBS News) Federal agents Nary and Jamie, who have been posing as kindergarten teachers on "The Amazing Race," had their cover blown in Sunday night's episode in Nairobi.

Border agents Art and J.J. told the other teams that they thought the two women were in law enforcement because of the terms they used in questioning the border agents about their jobs.

When the two confronted the women with their accusation, the federal agents held fast to their story - they were kindergarten teachers. (SPOILER ALERT)

Pictures: "The Amazing Race" 20

But the federal agents had more to worry about than a blown cover. They had great difficulty putting together a safari camp site and were last to arrive at the pit stop, which usually means elimination.

You have to admire their spirit, though. Knowing that the other teams were all ahead of them, they stopped on the way to the pit stop to watch a herd of elephants pass by.

Host Phil Keoghan had some good news for the two, however. It was a non-elimination leg of the race, so the federal agents are still in the game, although they will have to complete an added chore in the next leg.

First to reach the pit stop - for the fourth time this season - was Iraq vet Dave and his wife, Rachel who had resumed their bickering this week. They won a trip to Costa Rica.

Also doing some of their usual squabbling were divorcees Ralph and Vanessa. But the biggest confrontation was between the two Vanessas after Ralph of the dating divorcees team accused Brendon of the "Big Brother" team of shoving past him at the airport.

The bitterness between the two teams appears to run deep so there may be even more fireworks in the weeks to come as the field narrows in the race for the $1 million.

Who will win? Take our poll, discuss you choices in the comments below and return here next week for more commentary.