A trip to Canada's largest amusement park has left some Windsor students on high alert.

Music students at two Windsor elementary schools visited Canada's Wonderland this past Monday.

They enjoyed zipping through roller coasters, but they left the park on edge. Students say they were dealt counterfeit money.

It started when Connor Cosgrove, Grade 8 student at St. Jules school, stopped to get some lunch.

“I paid them the money and they gave me my money back, and I looked at the five and it looked a little different, but i just went with it," says Cosgrove.

So he carried on, not knowing what was about to happen.

“We went over to another concession stand to buy some ice cream, and they said ‘Do you have any other money?’ I looked at it and realized it was a counterfeit," says Cosgrove.

Turns out the same incident happened to another music student. He went to security to report his fake $10 bill.

“The security guard said I'm sorry there's nothing I can do about it," says Windsor Essex County District School Board music teacher Cecilia Calongcagong.

Calongcagong says both students got their bills from the same concession stand.

“The kids were looking forward to spending that extra money on the things they wanted to get," she says.

A report was filed with the head of security. Officials say the vendors who dealt with the students are employed by the amusement park.

“We take these situations so seriously, and that's why there's an incident report on hand, and measures are double checked to make sure nothing falls through the cracks," says Dave Phillips, vice president of marketing and sales at Canada’s Wonderland.

What was missing from both bills was a silver lining and when held up to the light, the face appeared to be missing.

“Ccounterfeiters have different way of operating, more likely for someone to accept a five with less skepticism than a 100 dollar bill," says Const. Michael Akpata.

Akpata says polymer notes help minimize counterfeit transactions.

“You'll see that they're made out of a plastic polymer, which makes it more difficult to copy,” says Akpata. “They've got a number of security threads, holograms, holographic features."

A counterfeit form was filled out, which will be sent along with the fake money to York Regional police.

Canada's Wonderland officials say employees at concession stands don't carry money on them and the fake bills likely came from transactions.

As an added gesture, CTV News has learned that Canada's Wonderful reimbursed the students with the $15.