Sorry to tell you this but the clinical practicum in Canada is different from the internship system in Australia. In Canadian RT schools, clinical spots are reserved for their students only from affiliated centres and no one from outside that class can apply. They're internal positions and they're assigned to students.
The best way to gain intern experience in Canada is to re-do the program. That being said job prospects vary greatly depending on what area your school is in. There're just enough jobs for most provinces except for Ontario probably. Those provinces would also give preference to their own residents/students when it comes to employment.
From what I've heard RT is quite in demand in Australia right? It may be the best for you to stay in Australia for now.
Hope this helps.