5 Continuity Mistakes Every GM Makes (and How to Catch Each One)

Campaign continuity mistakes fall into five recognizable types. That’s good news. “I might contradict something from six months ago” is a vague dread you can’t act on. A list of five specific failure modes is something you can actually check for in the ten minutes before a session. Here’s each type, how it shows up at a real table, and how to catch it before a player does.

1. The changing detail

A fixed fact about a person, place, or thing changes without a reason. The tavern keeper was Borin in session 4 and Gareth in session 19. The baron had a beard. The city gate was on the north wall.

Why it happens: most of these details were improvised. You invented the name in half a second while a player waited, and it never made it into your notes. Your players, meanwhile, wrote it in their character journal.

How to catch it: write down every improvised name or description right after the session, even as one line. Keep it in a short entry for that NPC or place, not buried in a session log, so you can find it in a few seconds when the party walks back into that tavern.

2. The dead who don’t stay dead

Something that changed in play gets forgotten. The NPC the party killed appears in your prep. The bridge they burned is crossed in the next arc. The item they sold is back in the villain’s hands with no explanation.

Why it happens: your notes describe the world as you planned it, not as it is after the players got to it. Prep from two weeks ago doesn’t know what happened last Thursday.

How to catch it: after each session, mark what changed and which session it changed in. status: dead (session 2) makes it obvious that your session 3 scene where Old Wren greets the party at the dock is broken. Before running any scene, check the status of every NPC in it. (The full routine is in how to keep track of your D&D campaign.)

3. The leaked secret

An NPC acts on a secret the party never discovered, or your recap mentions a twist the players haven’t found yet. The cult leader greets the party by their real names, which nobody told him. Your Discord recap says “after the mayor’s betrayal” when the betrayal is still three sessions away.

Why it happens: you know everything, all the time. Separating what’s true from what the players know is hard work, and under prep pressure it slips.

How to catch it: mark secrets as secret in your notes, and record the session in which the party learned each one. Before you post a recap or run a big scene, check it against the list of what’s still hidden. This mistake is the most painful one on this list, because you can’t take it back once it’s out.

4. The tangled relationship

Who works for whom, who owes whom, and who knows whom. Two NPCs you established as rivals are suddenly old friends. A faction that turned hostile in session 8 sells the party supplies in session 12. A quest giver forgets they hired the party.

Why it happens: relationships are the least written-down facts in any campaign. An NPC’s name sits in one line of your notes. “The Harbor Guild hates the watch captain because she arrested their boss” is spread across five sessions and lives mostly in your head.

How to catch it: record relationships as their own facts, linking the two entries. The Drowned Choir wants the Sunken Crown. Hollis Brand hired the party. Captain Marr distrusts the mayor. Before any scene with two factions in it, glance at how they’re linked.

5. The broken house rule

Your setting has rules, and the plot quietly breaks one. Resurrection magic doesn’t exist in this world, until the session where the villain needs a comeback. Teleportation can’t cross the sea, except this one time. The party’s homebrew injury rules get forgotten for a whole arc.

Why it happens: rules are promises to the table, and players notice when promises bend. A GM under pressure to make a scene work reaches for the shortcut and forgets the promise.

How to catch it: write your setting and house rules down as short, explicit entries, not lore paragraphs. Re-check them whenever a session touches magic, travel, or death.

Why these survive

All five share one cause: the gap between a fact and its contradiction is usually weeks of real time and several sessions of play. Human memory is worst at exactly that distance, and your notes only help if you think to look something up. The mistakes that reach the table are the ones you were sure about.

Your players, meanwhile, remember everything, especially anything their character cares about. That’s not a flaw. It’s the best sign they’re invested. It just means a contradiction costs you more than it would in any other kind of storytelling.

Catching them without rereading every session

You can check all five by hand: short entries for every NPC and place, changes recorded by session, a secret list with reveal dates, relationships written as links, and rules written as rules. That works. The tedious part is the cross-referencing, which is mechanical, and that’s what StoryGuard automates. After each session it proposes the codex updates from your notes, it checks new sessions against what you’ve already established, and it warns you before a recap gives away a secret the party hasn’t found. For how that works under the hood, see how AI reads your session notes. And if one of these mistakes has already reached your table, here’s how to retcon it gracefully.