Follow me, reader!--One of the few cases where the narrator addresses the reader directly. The connection between parts I and II with a repeated line echoes the connections between the Yershalaim and Moscow parts of the novel.
let me tell you the secret. . . Margarita--Bulgakov continues the pattern of giving characters' names after we have been introduced to them. Only the Master's name remains unknown (though the names of Woland's band are merely possibilities).
mimosa--like Margarita's name, we now learn the name of the yellow flowers the Master couldn't remember in Chapter 13.
a log hut--To a Russian reader it would be clear that Bulgakov is describing the Master either in camp or in exile. The scene may reflect the fate of Bulgakov's friend S. S. Topleninov, who was exiled to Vel'sk in the Arkhangelsk region for a year and a half in the early 30s. (Sokolov)
trolleybus along the Arbat--Russian trolleybuses are electric like trams, but they run on tires, rather than tracks. Trolleybus No. 2 used to run along the Arbat. Public transport lines were moved to Kalininskii Prospect (now Novy Arbat) when it was constructed in the 1960s; today Arbat is a pedestrian street.
a certain distinguished foreigner . . . street pimps--It was very common for the NKVD and later the KGB to use sex to entrap foreigners or extract secrets from them. Margarita naturally assumes this is what she is meant to do.
I'm supposed to sleep with him--A double pun: Margarita persists in thinking she is being drafted to work for the NKVD; at the same time in traditional witch-lore, communion with the Devil always meant sexual intercourse as well.