When Canada's Wonderland opened in 1981, there were several plans that never came to life.
There was going to be a themed area called "Frontier Canada" located where Splash Works is now. In addition the Mighty Canadian Minebuster (which had already been built) there was going to be a steam train ride, another log flume/water ride, a mine train coaster, a restaurant, an arcade and a lumberjack show (lumberjacks in Toronto?). Instead, they built White Water Canyon with theming partially intact.
There was also supposed to be a killer whale show (shades of Marineland) where the Kingswood Music Theatre is now.