In writing Hamlet, Shakespeare appears to have embedded lines that comment on the play itself.Connect these lines, in which Shakespeare appears to...

Shakespeare often created lines of text and situations in
his plays that mirrored the theatrical world in which he worked:  boy actors who played
women dressing as boys, plays within plays, and comments on the Globe (meaning both the
world in which man lives and the theatre building in which the actors performed).  So, I
can definitely provide you scenes and lines that make reference to and comment on the
theatrical world of the play.

The first, most obvious
comment is made by Hamlet to and with the troupe of Players who arrive at the castle. 
In Act II, scene ii, after the First Player has given his speech about Hecuba, Hamlet
has a soliloquy in which he comments on what the First Player has been able to do, that
he is unable to do.  He says:

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. . .What would he
do

Had he the motive and the cue for
passion

That I
have?

This suggests that the
actor playing Hamlet (along with the character himself) is
commenting on the other actor's (the one giving the speech as the
First Player) ability to be genuinely moved by imaginary circumstances, while he
cannot.  Of course, there is also the meaning regarding the character Hamlet's situation
in the plot of the play.

This commentary on the play itself
continues when Hamlet prepares the Players for thier performance before Claudius.  In
Act III, scene ii he is giving advice to the characters "The Players", but also,
potentially, to his fellow actors playing "The Players."  He
says:

O, it
offends me to the soul to hear a robustious peri-wig-pated fellow tear a passion to
tatters, to very rags, to split the ears of the groundlings, who for the most part are
capable of nothing but inexplicable dumb-shows and
noise.

Here he lays into one
of the actors (Maybe the First Player who displayed all the tears and emotion back in
II, ii?) for being too over-the-top emotionally.  He also addresses the real life
audience when he comments on the groundlings.

And then,
during the performance of Hamlet's play in Act III, scene ii, The
Mousetrap, the characters make comments about Hamlet's play that are also
comments on the situation of the play itself.  The most notable of these is when
Gertrude says, "The lady doth protest too much, methinks."  This statement could easily
describe Gertrude's own words in the scene that she has in her closet with Hamlet that
will follow the play as well as the words of The Player
Queen.

Shakespeare often made reference to the theatrical
world that his plays existed in through the text and actions of his characters.  In
Hamlet, much of this commentary revolves around the arrival of The
Players to the castle and their performance of The Mousetrap. 
Please follow the links below for more on the play-within-a-play in
Hamlet.