I’d missed this the first time I watched the Poison Sky last week! I know, I’m probably the last person to notice it…
In the Tardis, just before Donna looks at the monitor, there is a brief flash of Rose calling the Doctor - just for a few frames. Often the ‘story arcs’ throughout the season get on my pip, usually because they’re loud and obvious, but these brief flashes of Rose are really well done. Yay!