The animation in this film re-creates the "xerographed" style of 1960s and 70s Disney productions, in which rough pencil sketch lines are visible in the animation. This vintage look was achieved using the same software that was used to re-create this style in Mary Poppins Returns (2018).
The following firearms are seen used by the characters: Serafine's personal weapon is a 1918 Browning Automatic Rifle; Freckle uses an M1921AC Thompson (Tommy Gun) to attack the Marigold gang; Mordecai's signature weapon is a Colt 1911 pistol; the pistol that Freckle finds hidden under the seat is a Henrard Vici Pocket Pistol (indicated by the reversed rails and takedown lever), and Nicodeme's revolver might be a Colt 1917 or Colt Official Police (indicated by the distinctive shape of the hammer).
The Lackadaisy crew's car is a 1927 Ford Model A.