Prior to the release of Star Wars: The Force Awakens, it was reported that R2-KT, the droid created in honor of Katie Johnson, would appear somewhere in the movie.
Where did R2-KT appear in the movie?
...in the last 10 to 12 minutes of the film, in the bottom right corner of the screen, at the resistance base...
...after the destruction of Starkiller Base but before Rey leaves to find Luke.
There may be another appearance, but this is the only one I managed to catch.
Journalist Becki Hawkes of The Telegraph enlisted the aide of the Twitterverse to catalogue all the instances of R2-KT in The Force Awakens. Apparently, the droid appears 3 times:
Behind Poe Dameron’s ship during the scene in which he runs towards Finn (we were obviously too distracted by their joyful reunion to notice)
A second time, at the [Resistance] base, on the lower right hand side of the screen
At the [Resistance] base at the end of the film, when a injured fighter is being loaded on to a transporter
The third instance above is the one that I originally mentioned.