The source code for object Nil (listing 22.1) and case class :: use the
override modifier for isEmpty but not for head and tail.

According to section 10.8 the override modifier is mandatory in Scala and
chapter 22.1 introduced isEmpty, head and tails as abstract methods in
class List.

The package for the ListBuffer class should be scala.collection.mutable
instead of scala.collection.immutable

On page 477, in the first line of body of the method '+=', we have:
if (exported) copy()

I checked the scaladoc of the class ListBuffer, but I did not any method
called 'copy()', where is it defined?

In the code listing 25.3 it can be read:
"def map[B, That](p: Elem => B)(implicit bf: CanBuildFrom[B, That,
This]): That" since CanBuildFrom definition is "CanBuildFrom[-From,
-Elem, +To]" I expected to read "...(implicit bf: CanBuildFrom[This, B,
That]): That" so I downloaded Scala's source code and found the
definition was wrongly typed in the book. On the other hand, the function
parameter name is "p" whereas it is referred as "f" below.