The two stars were spotted Saturday morning in NYC, sporting their retro clothing as they taped scenes for the Amazon Prime smash hit.
Brosnahan, who plays Miriam "Midge" Maisel, and Borstein's character of Susie appeared to be loading up a car with goods, including huge boxes of Karo syrup ... and even a very large supply of Pursettes -- a vintage brand of tampons.
It's possible Midge and Susie are stocking up for a trip down south, as a new location for the stars was just announced.
"Pack your swimsuits because #MrsMaisel is heading to Miami!" the show announced earlier this week.
They also teased the imminent premiere of the third season by showing an airline departure board and revealing that Midge, "is getting closer to embarking on her next journey."
Along with filming new episodes, "The Marvelous Mrs. Maisel" has been in promotion mode as they campaign for the multiple Emmy nominations they recently picked up.
Earlier in the week, Amazon rolled back the prices around several Hollywood locations to what they would have been in 1959, including a gas station that was pumping out gasoline for .30 cents per gallon.
The rush for cheap tankfuls was so great that cops ended up shutting down the scene over traffic buildup.
"Maisel" has been crushing awards season since 2017, and has already racked up a slew of Emmy nods.
Brosnahan is once again nominated for Best Lead Actress, as well as Best Supporting nominations for Borstein and co-stars, Marin Hinkle and Tony Shalhoub.
The Amy Sherman-Palladino series is also nominated for Outstanding Comedy Series.