Like many seasons before it, an episode will oftentimes conveniently be a non-elimination round if a more important character happens to have placed last.
Rock & Spud placed near the bottom of the rankings in almost every leg in the first few episodes, and have skirted elimination on multiple occasions, yet they keep on surviving due to either other teams making game-ending errors or certain legs of the race being non-elimination. This is even discussedIn-Universe, as Rock points out their consistent poor performances to Spud. Rock steps up his game, getting them a few deserved higher placements around the midgame, but Spud... not so much. Ultimately, their elimination inverts this, with them being taken out by a completely-unprecedented double elimination after seemingly beating Chet and Lorenzo, after only placing so low in that particular challenge due to a few freak accidents.
Ryan & Stephanie, despite having worse teamwork skillsand acting more immature than the Stepbrothers, somehow kept avoiding elimination and made it to 6th place. They came within a hair's breadth of being eliminated in an early leg only to beat Tom & Jen in a footrace to the Chill Zone, and survived two utterly disastrous legs, including arguably the worst-run leg of the entire race, thanks to them turning out to be non-elimination rounds meaning that they technically lost the race a total of two times before being eliminated.
Jacques and Josee, the season's antagonists, received more penalties than any other team, and yet still managed to stay in the race. The most blatant/notorious examples are in "How Deep Is Your Love" and "Darjeel with It" which are back-to-back episodes. In the former, Josee sabotages the Sisters during the challenge by stealing their ball and knocking out Kitty's light on her hard hat which they're penalized a half-hour for, only to still end up placing 1st. In the latter, they get an hour-long penalty for decoupling the rest of the teams' train cars, and the Daters stop right before the Chill Zone to tell Don that they're dating again and make out just long enough for the Ice Dancers' penalty to end, and allow them to jump onto the carpet. Mercifully, they are eliminated in the finale and place third.
