Two teenage boys had to be rescued from the slingshot ride after one of the bungee cords malfunctioned and sent the roll cage they occupied hurtling into a metal beam. Source
Accidents
Theme parks and roller coasters are statistically very, very, very safe. Out of the millions of people who ride the thousands of rides every year, there are only a small handful of incidents. You are statistically more likely to be involved in an accident driving to an amusement park than having one at a park. The rarity of accidents is one reason why the media report them, similar to plane crashes.
Every important element of a ride is inspected on a regular basis and every ride is tested every day without passengers before it opens. A ride might not open, or a safety system might activate, if there is an imperfection. For theme parks to operate, they must obtain insurance and one stipulation is their rides are frequently inspected and signed off by a strict Health & Safety governing body. Every theme park does what they can to prevent accidents because the negative press would be bad for business.
Having said all that, theme park accidents still happen…
Ice Skater, Winter Wonderland, Cardiff, Wales
Three adult sisters were ejected from the funfair’s King Sizzler ride and were rushed to a hospital with serious injuries, including broken legs and ribs. Source
Evolution, Hannibal Park, Hammam Sousse, Tunisia
A 19-year-old woman was seriously injured after falling from the Fabbri rotating 360° pendulum ride and was transported to a local hospital where she underwent back and leg surgery.
Crazy Wave, Ban Nam Chan Fair, Krabi, Thailand
A 34-year-old woman and four children aged between 10 and 15 were thrown from the Magic Carpet style ride manufactured by Saucon of Vietnam, after an employee failed to lock the safety bar on the middle carriage. The children suffered minor injuries, but the woman was hospitalized with a broken arm and pelvis. Source
Fairy Swing, Halloween Fair, Urdaneta City, Philippines
A 13-year boy was hospitalized after suffering serious injuries when he fell from the high-speed wave swinger style ride. The teenager underwent pneumonectomy to remove one of his lungs due to the impact. Source
Sky Flyer, Expo Fair, Teloloapan, Guerrero, Mexico
Twenty-five people were injured when an aerial swing ride collapsed and fell approximately 20 feet (6m) at the “Day of the Dead” fair. Source (in Spanish)
Frisco Silver Dollar Line, Silver Dollar City, Branson, Missouri
Six guests and one employee were transported to hospital with minor injuries when the park’s stream train derailed. Source
Wacky Worm, Senor del Nicho Fair, Tlapa, Guerrero, Mexico
An approximately 30-year-old woman died after she was electrocuted by cables of the kiddie coaster, which caused her to be flung from the vehicle and hit her head on the ground. Source (in Spanish)
Treetops Rollercoaster, Oakwood Theme Park, Wales, UK
Remolino, Izamal Fair, Yucatan, Mexico
A 32-year-old man and a woman were ejected from the Himalaya/Matterhorn style ride after a screw broke from the seat lock. Both guests fell several meters to the ground and were transported to hospital with head injuries. Source (in Spanish)