Peter Labuza’s review published on Letterboxd :
Out Of The Inkwell Films, most famous for their Betty Boop and Popeye cartoons, was the brain child of Max and Dave Fleischer, father and uncle respectively of the recently sort-of-rescued-from-obscurity auteur Richard Fleischer (in fact, Richard wrote the history of Inkwell—"They say it's difficult being a famous man's son...I didn't find it difficult at all."). A film like Bed Time was actually an early example of the Rotoscope technique now recognized for films like Richard Linklater's Waking Life. Max would film Dave in a clown suit, and then use the materials to then trace a character in motion.
Bed Time is perhaps most fascinating for Koko The Clown's ability to penetrate the non-animated space, as Koko jumps from his canvas into the real world, a technique that recalls Who Framed Roger Rabbit?. The gambit becomes obvious to the discerning viewer—Koko is the only one to move in the frame, and thus he's clearly been painted into still photographs. But because we tend to always view any special effects from the silent era with a disbelief ("How did they do that without computers?), it becomes a delightful curiosity.