Can You Find the Grammar Error?

[3]   Barrel riders know how important it is to quickly leave the starting gate.

       Correction: Trick question. There is no error. The rule against split infinitives died somewhere back in the 1890s. How else can we expect “to boldly go where no man has gone before”? However, you could improve this sentence by putting “quickly” at the very end of the sentence – not to avoid a split infinitive but to add punch.