diff --git a/src/borrowing/interior-mutability/refcell.md b/src/borrowing/interior-mutability/refcell.md
index 41dfdd84a177..8c38659a11e9 100644
--- a/src/borrowing/interior-mutability/refcell.md
+++ b/src/borrowing/interior-mutability/refcell.md
@@ -47,7 +47,7 @@ fn main() {
 
 - The extra block in the example is to end the borrow created by the call to
   `borrow_mut` before we print the cell. Trying to print a borrowed `RefCell`
-  just shows the message `"{borrowed}"`.
+  just shows `RefCell { value: <borrowed> }`.
 
 ## More to Explore
 
diff --git a/src/iterators/collect.md b/src/iterators/collect.md
index 5fd989404813..992ab9d4d541 100644
--- a/src/iterators/collect.md
+++ b/src/iterators/collect.md
@@ -24,7 +24,7 @@ fn main() {
 
 <details>
 
-- Any iterator can be collected in to a `Vec`, `VecDeque`, or `HashSet`.
+- Any iterator can be collected into a `Vec`, `VecDeque`, or `HashSet`.
   Iterators that produce key-value pairs (i.e. a two-element tuple) can also be
   collected into `HashMap` and `BTreeMap`.
 
diff --git a/src/iterators/helpers.md b/src/iterators/helpers.md
index cbb51b1328cf..e42dd1dd60e6 100644
--- a/src/iterators/helpers.md
+++ b/src/iterators/helpers.md
@@ -34,7 +34,7 @@ fn main() {
   where you can find all the documentation about them.
 
 - Many of these helper methods take the original iterator and produce a new
-  iterator with different behavior. These are know as "iterator adapter
+  iterator with different behavior. These are known as "iterator adapter
   methods".
 
 - Some methods, like `sum` and `count`, consume the iterator and pull all of the
diff --git a/src/lifetimes/exercise.rs b/src/lifetimes/exercise.rs
index 3e0e0a551bed..87dfe2d10365 100644
--- a/src/lifetimes/exercise.rs
+++ b/src/lifetimes/exercise.rs
@@ -88,7 +88,7 @@ impl<'a> FieldValue<'a> {
 
 /// Parse a VARINT, returning the parsed value and the remaining bytes.
 fn parse_varint(data: &[u8]) -> (u64, &[u8]) {
-    for i in 0..7 {
+    for i in 0..10 {
         let Some(b) = data.get(i) else {
             panic!("Not enough bytes for varint");
         };
@@ -103,7 +103,7 @@ fn parse_varint(data: &[u8]) -> (u64, &[u8]) {
         }
     }
 
-    // More than 7 bytes is invalid.
+    // More than 10 bytes is invalid.
     panic!("Too many bytes for varint");
 }
 
diff --git a/src/modules/encapsulation.md b/src/modules/encapsulation.md
index 7d28977ffefb..a3ae79702089 100644
--- a/src/modules/encapsulation.md
+++ b/src/modules/encapsulation.md
@@ -75,7 +75,7 @@ fn main() {
 ## More to Explore
 
 - If students want more information about privacy (or lack thereof) in enums,
-  you can bring up `#[doc_hidden]` and `#[non_exhaustive]` and show how they're
+  you can bring up `#[doc(hidden)]` and `#[non_exhaustive]` and show how they're
   used to limit what can be done with an enum.
 
 - Module privacy still applies when there are `impl` blocks in other modules
diff --git a/src/pattern-matching/destructuring-structs.md b/src/pattern-matching/destructuring-structs.md
index 66f3289316c6..4e8f5e941c1c 100644
--- a/src/pattern-matching/destructuring-structs.md
+++ b/src/pattern-matching/destructuring-structs.md
@@ -36,7 +36,7 @@ fn main() {
 <details>
 
 - Change the literal values in `m` to match with the other patterns.
-- Add a new field to `Movement` and make changes to the pattern as needed.
+- Add a new field to `Move` and make changes to the pattern as needed.
 - Note how `delta: (x, 0)` is a nested pattern.
 
 ## More to Explore
diff --git a/src/pattern-matching/exercise.md b/src/pattern-matching/exercise.md
index 095e3d192bde..74d65317e18c 100644
--- a/src/pattern-matching/exercise.md
+++ b/src/pattern-matching/exercise.md
@@ -71,7 +71,7 @@ Create a new Cargo library project with
 cargo new --lib evaluator
 ```
 
-Copy and paste the code below into a the `src/lib.rs` file.
+Copy and paste the code below into the `src/lib.rs` file.
 
 Then begin implementing `eval`. Use `cargo test` to ensure that the final
 library passes the tests. It may be helpful to use `todo!()` and get the tests
diff --git a/src/unsafe-rust/unsafe-functions/extern-c.md b/src/unsafe-rust/unsafe-functions/extern-c.md
index 80a025032e76..2298c6c0ae49 100644
--- a/src/unsafe-rust/unsafe-functions/extern-c.md
+++ b/src/unsafe-rust/unsafe-functions/extern-c.md
@@ -7,8 +7,9 @@ SPDX-License-Identifier: CC-BY-4.0
 
 You can declare foreign functions for access from Rust with `unsafe extern`.
 This is unsafe because the compiler has no way to reason about their behavior.
-Functions declared in an `extern` block must be marked as `safe` or `unsafe`,
-depending on whether they have preconditions for safe use:
+Functions declared in an `extern` block can be marked as `safe` or `unsafe`,
+depending on whether they have preconditions for safe use. Functions without
+either qualifier are `unsafe` to call:
 
 ```rust,editable
 # // Copyright 2025 Google LLC
diff --git a/src/unsafe-rust/unsafe.md b/src/unsafe-rust/unsafe.md
index 082199aca808..868d7cb7bd8b 100644
--- a/src/unsafe-rust/unsafe.md
+++ b/src/unsafe-rust/unsafe.md
@@ -29,7 +29,7 @@ Unsafe Rust gives you access to five new capabilities:
 - Implement `unsafe` traits.
 
 We will briefly cover unsafe capabilities next. For full details, please see
-[Chapter 19.1 in the Rust Book](https://doc.rust-lang.org/book/ch19-01-unsafe-rust.html)
+[Chapter 20.1 in the Rust Book](https://doc.rust-lang.org/book/ch20-01-unsafe-rust.html)
 and the [Rustonomicon](https://doc.rust-lang.org/nomicon/).
 
 <details>