Panel 2: The pink background utilized here by John Higgins subtly emphasizes Jon’s statement in this panel: “I am on Mars,” which has been colored this shade by Higgins.
Panel 3: With Laurie’s dialogue in this panel – “…it’s all so deus ex machina…” – Moore is commenting on his own story and the choice he has made here. Deus ex machina comes from the tendency in Greek and Roman tragedy of introducing a god by means of a crane to decide the final outcomes and, in contemporary terms, is a moment in a drama when a person or thing suddenly and unexpectedly appears to provide a contrived solution to an insoluble difficulty. Moore is acknowledging the contrivance Jon’s return at this particular moment in time is – a result of the god-like powers Dr. Manhattan wields.
Also, as Dr. Manhattan notes the direct translation of the Latin phrase – “the God out of the machine” – he is literally that: a god-like being who has come out of the machine-like sanctuary he created on Mars.