If you crash your car on a track, and then rewind and continue from an earlier point, the game will give you a prompt stating that you cannot get on the highscore table if you continue. Thus, ostensibly, it would be easy to prove whether replay handling was used simply by asking participants in a competition to send in the .hig file of the track along with the .rpl file. This was tried in some early competitions like Charles' Competition. However, .hig files are very easy to edit, so this did not work.
Then, in the late 90's, Lukas Loehrer invented the program called RPL Info, which can determine from the file whether a replay is continued or not. This was considered a sufficient way of proving whether replay handling was employed, until it was discovered that if you save a replay before having finished it, and then load and continue from the end of the unfinished replay, it is not considered continued by the game, and thus not by RPL Info either.
Most competitions continued to rule out continued replays, but allowed this replay-saving trick, as there was no way to prove that it had been done. Then finally, in October 2002, Mingva revealed the secret of what came to be known as advanced replay handling, and that was the end of RH rules in all competitions until 2005. It is possible to continue a replay as much as you like, and then simply fool the game and RPL Info by continue from maybe 1 second before the finish line, saving the replay 0.2 seconds before the finish line, loading and continuing from there. At this discovery, ZakStunts and other major competitions decided to allow continued replays, considering it foolish to require of racers to make the above described procedure.
In late 2009, Cas made another attempt to solve the RH verification problem with a project he called Vizcacha. Unfortunately, the project was abandoned when the strategy it had been based upon proved unreliable.