This feature allows skaters to "level out" aka orient themself horizontally in the air to prevent bailing. The skater can grab onto the rear bumper of a vehicle (much like Marty McFly in Back to the Future), moving to either end of the bumper to avoid obstacles. Known in THPS3 as hidden combos, it was refined and extended, adding double-tap variation for almost each trick in the game. For example hippo will cause Hippo Plant, Lion will "eat" skater and Elephant can be skitched. While most of them act as pedestrians, some of them may implement vehicle features.
THPS4 was the first game in series to feature mammal animals. Usually it's a kicker or a quarter-pipe, but some maps provide more complex constructions. Unique in THPS4 - each map provides up to seven skate objects that can be toggled by player. However, it got rid of Control Zone and Keep Away game modes from THPS3.
THPS4 instead featured a Career mode more similar to Free Skate mode, in which there was no time limit to explore the level, and the goals are given by characters found throughout the levels when the player talks to them. The game is a departure from the previous three games' Career mode, in which the player had a set amount of time in order to find and complete goals.