BC Place looks a bit like a toilet lid:
https://www.google.ca/maps/place/BC+Place/@49.2767972,-123.1130451,368m/data=!3m2!1e3!5s0x5486717ce3307959:0xbb811745f65fed95!4m6!3m5!1s0x5486717cfcbee0d5:0xf9404dfd918218bb!8m2!3d49.27675!4d-123.111999!16zL20vMDNiNGcz?entry=ttu
McMahon doesn't have a roof, so no, doesn't look like a toilet: seat:https://www.google.ca/maps/place/McMahon+Stadium/@51.0705269,-114.1220417,421m/data=!3m2!1e3!5s0x53716fa41ee999fd:0x3333a570bd07a8ec!4m6!3m5!1s0x53716fa404414271:0xf0f4b301ee305ac8!8m2!3d51.0704555!4d-114.121497!16s%2Fg%2F11bc65sdpl?entry=ttu
Commonwealth same as McMahon, but bigger:
https://www.google.ca/maps/place/Commonwealth+Stadium/@53.5597173,-113.4779618,563m/data=!3m2!1e3!5s0x53a02301b52feec1:0x3333a57040c9561c!4m6!3m5!1s0x53a02301d7e91b65:0xccd3bd3956bf7a03!8m2!3d53.5597052!4d-113.4768787!16zL20vMDM4d2dy?entry=ttu
Mosaic definitely looks like a public toilet seat:
https://www.google.ca/maps/place/Mosaic+Stadium/@50.450613,-104.6343478,427m/data=!3m1!1e3!4m6!3m5!1s0x531c1e69ca22280d:0xf2ea51d252b531ae!8m2!3d50.4504947!4d-104.6329603!16zL20vMDFfa3B4?entry=ttu
Princess Auto Stadium doesn't have a round roof at all:
https://www.google.ca/maps/place/Princess+Auto+Stadium/@49.8078139,-97.143562,433m/data=!3m1!1e3!4m6!3m5!1s0x52ea7377de57b1bb:0x90cef9b21669335b!8m2!3d49.8076999!4d-97.1431117!16s%2Fm%2F03qhnh4?entry=ttu
BMO Field looks like a box:
https://www.google.ca/maps/place/BMO+Field/@43.6333329,-79.4192868,485m/data=!3m1!1e3!4m6!3m5!1s0x882b3505f6ef4351:0x9d2169b3f7b70c2d!8m2!3d43.6331702!4d-79.4186162!16zL20vMDh3Z2Z4?entry=ttu
Tim Horton's Field also looks like a box:
https://www.google.ca/maps/place/Tim+Hortons+Field/@43.2522076,-79.8302848,488m/data=!3m2!1e3!5s0x882c9bfd59645a2f:0x3333a570d213c5fc!4m6!3m5!1s0x882c9bfd5ec2c495:0xd057f19def0bffe9!8m2!3d43.2524552!4d-79.8308998!16s%2Fm%2F09gh8gh?entry=ttu
TD place is pretty square as well:
https://www.google.ca/maps/place/TD+Place/@45.3982322,-75.6846403,396m/data=!3m1!1e3!4m6!3m5!1s0x4cce05c1c34168f3:0x4a69b90dfe9b6eb2!8m2!3d45.3984036!4d-75.6835728!16zL20vMDNiN3ox?entry=ttu
Percival Molson Stadium is similar in shape to McMahon and Commonwealth:
https://www.google.ca/maps/place/Percival+Molson+Memorial+Stadium/@45.5101881,-73.5811302,279m/data=!3m1!1e3!4m6!3m5!1s0x4cc91a36e15778c9:0x25493c3f356f3ea6!8m2!3d45.5101363!4d-73.5807716!16zL20vMDM5MTli?entry=ttu
So yeah, only Mosaic looks like a toilet seat, and the closest other one is the lid that is BC Place.