Keaton's third feature under his own steam is an incredible technical accomplishment, but also an almost Pirandellian exploration of the nature of cinematic reality. Buster plays a cinema projectionist, framed for theft by a jealous rival for his girl's hand, who daydreams himself into life as a daring detective. In an unforgettable sequence, Buster (actually fallen asleep beside the projector) forces his way onto the screen and into the movie he is projecting, only to find himself beset by perils and predicaments as the action around him changes in rapid montage. The sequence is not just a gag, but an astonishingly acute perception of the interaction between movie reality and audience fantasy, and the role of editing in juggling both. The timing here is incredible (a technical marvel, in fact); even more so in the great chase sequence, an veritable cascade of unbelievably complex gags (like the moment when Buster, on the handlebars of a riderless, runaway motor-bike passing some ditch-digging roadworks, receives a spadeful of earth in the face from each oblivious navvy in turn). It leaves Chaplin standing.
[Tom Milne, Time Out]