The original manuscript here has the plural prisons. When Oliver Cowdery copied the text from 𝓞 into 𝓟, he accidentally replaced this plural with the singular, prison. All the printed editions have continued with the singular. Elsewhere the text has only the singular prison when the verb is cast (with 40 examples of either “cast in(to) prison” or “cast out of prison”). But all of these examples refer to cases where specific people were put in prison. Here in Alma 46:23, we have a general list of punishments. There are two other passages that include similar lists, and both of these read prisons in the original text:
In these two cases, the verb is deliver rather than cast, but that is not the determining factor. The critical text will restore the original plural prisons here in Alma 46:23 as well as in Alma 36:27 (see the discussion under that passage).
Even when we have the phrase “cast into prison”, the context can be plural; in such passages, the text may later refer to plural prisons:
These two examples show the strong tendency for the verb cast to take the singular prison, even when the context implies plurality. Still, there is one example in the earliest text where “cast into prisons” occurs (namely, here in Alma 46:23).
Even though the 1830 edition was proofed against 𝓞 for this part of the text, this passage retained the singular reading prison, the reading in 𝓟. Perhaps the phrase “cast into prison” was so highly expected that Oliver Cowdery, the proofreader, missed seeing the plural s. Or perhaps he thought the plural prisons was simply an error (yet he did not cross out the plural s in 𝓞).
Summary: In accord with the reading of the two manuscripts, restore the plural prisons in Alma 46:23; the original plural agrees with other examples where prisons is found in a general list of punishments (in Alma 36:27 and in Alma 62:50).