In the commentary for this episode, Russell T. Davies stated that he prefers the Doctor in the blue suit when going to the future and the brown suit when going to the past.
"42" may also be seen as reference to the Ultimate Answer to Life, the Universe and Everything, as written by Douglas Adams in the radio series "The Hitchhiker's Guide to the Galaxy". Some of the sound effects in this episode were taken from The Hitchhiker's Guide to the Galaxy (1981) TV show. Adams also wrote scripts for several Doctor Who (1963) episodes during the late seventies. Interestingly, in one of the "Hitchhiker's Guide" books there is also a chapter where the protagonists are caught in a stolen spaceship headed for the sun.
Martha Jones gets her phone upgraded and a key to the TARDIS, two signs that she's the new companion.
This episode takes place in the 42nd century.
This episode ostensibly (though not quite) takes place in real time, a technique made famous by 24 (2001). The average running time of a Doctor Who episode also happens to be about 42 minutes.