By Koundinya, founder of Bunsho · 29 September 2026
We hid 18 mistakes in Great Expectations. Here's what Bunsho found.
I write novels as well as software, and the thing that keeps me up at night is not the plot. It is the small stuff: the scar that moves arms, the character who knows something she was never told. So we took one of the longest, most loved novels in English, broke it on purpose, and asked Bunsho to find the damage.
Why Great Expectations
It’s 59 chapters and close to 185,000 words. It spans decades of Pip’s life, a small village and half of London, and a cast you need a notebook to keep straight. If you wanted to check it for consistency by hand, you would be at it for weeks. That made it a fair test.
It’s also public domain, which matters. We used the Project Gutenberg edition (eBook #1400), split into its 59 chapters, with nothing else changed until we started planting mistakes. Anyone can download the same text and check our work.
What we did
We hid 18 mistakes in the text, the kind I have found in my own drafts more times than I’d like to admit. A name that changes halfway through. A number that grows. A woman who dies in one chapter and is standing at her window in the next.
Then we set 13 traps. These are passages that look like mistakes but aren’t: nicknames, Pip’s own lies, a burn that heals over time. Honestly, this was the part I cared about most. A tool that cries wolf is worse than no tool at all, because after the third false alarm you stop reading what it says.
Then we ran Bunsho on the whole book. Three times, from scratch, so you can see how consistent it is too.
How it went
| Run 1 | Run 2 | Run 3 | |
|---|---|---|---|
| Planted mistakes found | 11 of 18 | 13 of 18 | 15 of 18 |
| Traps it fell for | 0 of 13 | 0 of 13 | 0 of 13 |
| Time to check the whole novel | about 7½ min | about 7½ min | about 7½ min |
All three runs are there, the best and the worst. Across them, Bunsho found 16 of the 18 mistakes at least once. And it didn’t fall for a single trap, in any run.
That zero is the number I’m proudest of. We built Bunsho around an idea we call Proof of Contradiction: nothing gets called a mistake until it’s proven. So every issue arrives with the exact lines from both sides, and when the story already explains itself, Bunsho keeps quiet.
Every mistake we hid, and how often it was caught
Some of these are plain facts, like an age or a name. Don’t let that fool you. The two halves of each sit dozens of chapters apart, worded differently, in a book this long. You would never find them by searching for a word. The others need actual reasoning. Here is every one, including the two Bunsho never caught.
Details that drift across hundreds of pages
Miss Havisham's stopped clock
“twenty minutes to nine” becomes “a quarter past nine”. Chapter 8, then chapter 38. Caught in 3 of 3 runs.
Pip's dead brothers
“five little brothers” becomes “six little stones”. Chapter 1, then chapter 35. Caught in 3 of 3 runs.
Pip's sister
“more than twenty years older” becomes “but ten years older”. Chapter 2, then chapter 35. Caught in 3 of 3 runs.
Pip's age
“three-and-twenty” becomes “but one-and-twenty”. Chapter 39, then chapter 46. Caught in 3 of 3 runs.
Jaggers's face
“an exceedingly dark complexion” becomes a “fair, pale face”. Chapter 11, then chapter 48. Caught in 3 of 3 runs.
The village pub
The Three Jolly Bargemen becomes the Three Jolly Boatmen. Chapter 10, then chapter 18. Caught in 3 of 3 runs.
Biddy
She becomes “Betty”. Chapter 7, then chapter 58. Caught in 2 of 3 runs.
Wemmick's home
His “Walworth sentiments” become “Wandsworth sentiments”. Chapter 24, then chapter 45. Caught in 2 of 3 runs.
Joe's hair
“curls of flaxen hair” become “thick black curls”. Chapter 2, then chapter 57. Caught in 0 of 3 runs.
Mistakes you have to think about
Dead, then at the window
Joe tells Pip Miss Havisham is dead. In the next chapter she stands at her window watching men nail up the auction bills. Chapters 57 and 58. Caught in 3 of 3 runs.
Knowing too early
Herbert says Pip's money comes from the convict he fed on the marshes, nine chapters before anyone, Pip included, could know it. Chapters 30 and 39. Caught in 2 of 3 runs.
One shoe, then two
Miss Havisham wears “but one shoe” in a room where nothing has moved in decades, and later “both her white satin shoes”. Chapters 8 and 44. Caught in 1 of 3 runs.
A journey that takes no time
Pip's coach leaves at two o'clock and sets him down at “a quarter past three”, a journey of several hours. Chapter 28. Caught in 1 of 3 runs.
Rowing with a burned arm
Pip's arm is too burned to get a coat on, then he “pulled with both arms” at the oars. Chapters 52 and 54. Caught in 1 of 3 runs.
The burn changes sides
Pip's burned left arm becomes his “bad right arm”. Chapters 50 and 53. Caught in 0 of 3 runs.
Slips in the storytelling voice
A jump into someone else's head
A book told only by Pip suddenly reports another character's private thoughts. Chapter 33. Caught in 3 of 3 runs.
Pip in the third person
“Pip sat at the coach window”, in Pip's own first-person story. Chapter 43. Caught in 3 of 3 runs.
A slip into the present tense
“I come ashore at the old wharf”, in a story told in the past. Chapter 47. Caught in 3 of 3 runs.
The traps it left alone
A careless read would flag every one of these. None of them is a mistake, and Bunsho didn’t flag any.
Names the book gives on purpose
Herbert calls Pip “Handel”. Magwitch goes by Provis. Mr. Wopsle becomes Mr. Waldengarver on stage. Wemmick's father is “the Aged” and his house “the Castle”.
Pip's own lies
Pip invents a black velvet coach at Miss Havisham's. The book tells you he is lying, so Bunsho should stay quiet.
Change that happens on the page
Pip's burns heal over several chapters. Joe's flaxen hair is “a little grey” eleven years on.
The narrator looking back
Pip the adult speaks in the present tense about his younger self. That is how the book is told, not a slip.
A guess, marked as a guess
“I suppose he was about five-and-twenty.” An estimate cannot contradict a fact.
Three questions for Mr. Dickens
Here’s the part I didn’t expect. Outside everything we planted, Bunsho raised a few questions about Dickens’s own text. I’m not going to tell you Dickens made mistakes. These are the notes a good editor pencils in the margin, and I’ll leave the verdict to you.
Mrs. Brandley, or Mrs. Blandley?
The widow Estella lives with is “Mrs. Brandley” seven times, and “Mrs. Blandley” once, in the same chapter. Slip, or typesetter?
Does Jaggers laugh?
“‘Go it!’ said Mr. Jaggers, with a short laugh.” A few paragraphs later: “Mr. Jaggers never laughed.” Slip, or character?
Pounds or guineas?
Miss Havisham hands over “five-and-twenty guineas”. Joe announces “it's five-and-twenty pound”, and Pumblechook echoes him. A guinea is worth more than a pound. Slip, or Joe being Joe?
Where it fell short
It isn’t perfect, and I’d rather you hear that from me. Every run missed a few of our mistakes, and two of them it never caught at all. It also raised a handful of questions a careful reader would wave away. My favourite: Pip “resolved to leave the Avenger behind”, then turned up “attended by the Avenger”. He meant he wasn’t taking his servant on the trip. The servant still walked him to the coach.
Because every question comes with its lines, you settle a case like that in a few seconds. That’s the whole idea. Bunsho doesn’t decide for you. It shows you the evidence, and the story stays yours.
More on what Bunsho checks: the continuity checker and the plot hole checker. More posts on the Bunsho blog.
Now try it on your book
Bunsho is free to download for Mac and Windows. Bring your manuscript and see what it finds. Write fearlessly.