In the woods, Ciri rubs her hair in the mud for less visibility. When she enters the Cintra's camp, her hair is blonde again. The color continues to shift during later scenes.
Joey Batey as Jaskier is shown playing a traditional mandolin which is tuned G-D-A-E, but is shown playing chords in the style of traditional guitar tuning, E-A-D-G-B-E.
Live eel, if anything, are only yellow on the belly, and only young ones. Only smoked eel is golden-yellow all over.