halacha - Making a mistake in davening: when should one find out what to do?

There are lots of sections in the tefillah that either needed to be added at certain parts of the year or that one should cease saying at certain times of the year, as well as additions for Hanukkah, for Purim, for shabbes and for yontef. It's not unheard of that somebody who is used to davening a certain way might make a mistake, and s/he might not realise that they had done so until a paragraph or two has elapsed.

Accordingly, the rules that concern what a person should do in these situations are correspondingly varied, and many siddurim see fit to include them. Some print them, for example, at the back of the book, while some print them closer to the beginning. It's not too hard for a person to familiarise themselves with some of these rules, but there are a good few of them.

My question relates to a person who has made a mistake but does not yet know how that particular error is supposed to be fixed. As a general rule should they pause their tefillah, flick to the appropriate page and find out how to rectify their error? Is it better that they just keep davening and then learn afterwards what it is that they should have done? Or should they simply go back to the place where they had made the mistake (or even to the very beginning) and continue from there?

In my own experience, there is often a temptation to find out there and then how that particular error should be fixed, yet interrupting the davening to learn something (even though it doesn't necessitate movement or speech) seems improper.

Answer

Mishna Berura on SA OC 104 sk 2:

‏ (ב) בתפלתו ואפילו במקום הפסד ממון אין לו להפסיק. כתב הח"א כלל כ"ה סעיף ט' העומד בתפלה ונסתפק באיזה דין איך יתפלל כגון ששכח איזה דבר בתפלה מותר לילך ממקומו למקום מיוחד ולעיין שם בספר ואם מותר לשאול הדין צ"ע ונ"ל ‏דמותר (עד כאן לשונו של החיי אדם):‏

The Chaye Adam wrote (klal 25, paragraph 9): One who is praying and has a doubt about one rule concerning how to pray, e. g. what to do after he realizes that he had forgotten something; he is allowed to move from his place and to verify (for instance in a book). To ask someone is more problematic but it seems that it is permitted.

See also the whole pilpul in Nishmat Adam sk 1 at the bottom of the page (the decisive explanation is that something which is in connection with the continuing of the prayer is not an interruption).