Olesz was assessed a five-minute major and a game misconduct on the play.
Anthony Stewart scored his team-high third preseason goal and had an assist for Florida. Brett McLean also had a goal and an assist, and Kamil Kreps, Olesz and Nathan Horton also scored. Ville Peltonen had three assists as the Panthers scored three power-play goals.
Islanders starting goalie Rick DiPietro made his first appearance of the preseason and finished with 27 saves.
The Panthers ended the preseason with a 3-2-2 record. Monday s game was their only one at home in the preseason. The Islanders finished the preseason 4-3.
Vokoun's best saves came in the second period when he stopped Richard Park on a breakaway in the first minute and later stuck out his leg to stop Freddy Meyer's tip from the goal mouth.
The Panthers entered the game 1-for-32 on the power play in the preseason.
Olesz got the first power-play goal at 8:47 of the second period to make it 3-0. He tipped Bouwmeester's wrist shot from the top of the faceoff circle.
McLean and Horton added scores on the power play in the final two minutes of the game.