Breakfast Princess calls Lumpy Space Princess a 'pamplemousse'. Pamplemousse is French for grapefruit. When LSP attacks the maple guard, she does so with a grapefruit.
goof: Marceline is somehow out in broad daylight. She is supposed to be burnt by the sun. I suppose she was fine because it was dawn, but Marshal Lee, Marceline's Fiona&Cake counterpart, was burnt by a sunrise.
Neither Finn nor Jake appear in this episode.