I wish we could talk about the 'monkey challenge' -- which was a lot of fun -- instead of lost passports. (CBS)

On shows involving competition — whether it’s a game show or a reality show — there are certain rules that must be followed.

On Jeopardy!, you must always phrase your answers in the form of a question. On Survivor, never trust anyone fully. And on Rock of Love, drink as much as humanly possible so you increase the likelihood of embarrassing yourself.

There is one critical rule above all others on The Amazing Race: Never lose your passport.

While this has happened before in the 14 previous seasons of the CBS show — Dallas lost his to eliminate himself and his mom Toni in Season 13 — this might be the most heartbreaking example.

Zev and Justin, who had become one of the teams with the most personality in the race so far, had put together an incredible leg of the around-the-world race, getting to Phnom Penh, Cambodia and completing the necessary tasks well ahead of their competitors.

They reached the mat and all seemed well — host Phil Keoghan had done his interview with them, informing them of their first-place status — until Zev realized the problem. Somewhere along the course, he’d lost his passport.

The team searched all of their belongings, and even called upon their very helpful cabbie who had been a huge reason for Zev and Justin’s extremely good finish. But no luck.

Host Phil Keoghan (right) has some bad news for Zev and Justin. (CBS)

And so, Phil has to inform them that instead of winning the leg — Zev and Justin end up going home.

At least one site has raised the question as to why the producers wouldn’t let the guys search until the start of the next leg for the missing passport.

Unfortunately, that’s exactly what happened with Toni and Dallas in Season 13. If the travel documents aren’t in hand when you arrive at the checkpoint, the race ends for you.

At any rate, this doesn’t make it easier to deal with losing a great team like Zev and Justin. The two friends — who met at camp as kids — had a tremendous dynamic. And Zev triumphing over his Asperger’s syndrome to compete in such a tough race only added to things.

Now, you’re probably wondering what happened next. Fortunately, as you’ll see below in this week’s Elimination Station, things turned out OK for the boys: