Event cards can do a number of interesting things, but by far the most amusing is the ability to knock horses out of a race. If one of them is played while a horse is on that hedge, those horses can be knocked out of the race. This makes landing on hedges very risky. Often players will choose to move out a lane or two rather than stop on a hedge and risk being knocked out by a player with a sizeable bet on the horse that's trailing by a length. But that's not all.
Some cards force a horse to change lanes as far as possible before moving forward.
Some cards can, on a roll of doubles, discover that a winning horse had been illegally injected with steroids and disqualify the horse, moving the second and third place finishers up a notch. This gives the bearer the ability to knock out any horse practically at will. The player with the most cash after six races is the victor. The fun in this game comes from skillful use of horse position and event cards to muck about with the outcome of a race. Since the amount you've wagered on a horse is known, it's vital to keep the identity of your pick a secret lest someone knock it out to keep you from reaping any rewards.