My 3rd great grandfather William Johnson (16 Jun 1823 Holme On Spalding Moor, Yorkshire, England - 10 Oct 1905 Huron, Ontario, Canada) and his spouse Charlotte Colton (16 Feb 1822 [Bardney Lincolnshire?] England - 4 Oct 1888 Huron, Ontario, Canada) immigrated to Canada from Yorkshire, England about 1850. By the census in 1861 and for the rest of their lives, they lived and farmed in or around Morris or East Wawanosh, Huron county, Ontario.
Among my grandmother Olive's family history records is the back cover of a leather-bound volume on which is recorded the birth dates of William and his 13 siblings. (If only I were able to "Ask Olive!") The ex-volume is probably from the mid-19th century. I base this on the stamp "Watkins Binder" on the cover itself. Watkins was a bindery in London from the late 18th century to at least 1850.
Family groups often migrate together. Based on that, my question is this: Might have any of William's siblings also immigrated to Canada and can they be traced through government or church records?
The first part of this question is fairly easy - the short answer is "Yes" William's siblings could have stayed in England or emigrated to another country. Canada and Australia were often favourite locations for English emigrants.
As for finding William's siblings, I wouldn't advise you start on a random hunt in Canadian records. That would be hit and miss and you're working with some fairly common names.
My advice is to follow the standard genealogy method which is to start with an individual and trace that person. Usually you are searching backwards, finding ancestors of an individual. In your case you want to research forward.
What I mean by this is, you would take each of William's siblings in turn and track their lives in England. Find them in every census year you can. Look for deaths and marriages. Basically you are trying to prove or disprove that they lived and died in England.
So if you are searching them in census and they disappear and you can't find a death record, there's a possibility that they left the country. You might then have a hunt in ships passenger lists for a record of travel.
There is another challenge with a ships passenger lists search. Ships passenger lists arriving in Canada did not have to be kept until 1865. For help and links to online projects of Ships Passenger Lists before 1865 you may want to refer to Filling in The Gaps.
Other countries like Australia had other regulations and you would have to investigate to find out what ships passenger lists exist and where they can be found.
Another more obscure search would be in local newspapers in England. Let's say for example that a sibling or two disappear from English census records after 1851. If you could find a local newspaper for the area you might find reference to a family group leaving the community to settle elsewhere. That's a long shot but it is another avenue of research.
The bottom line is that you have a lot of slogging and digging into records ahead of you but it should be a very interesting journey!