Trivia: Director Martin Scorsese makes more then just a cameo in this film, he's the passenger that sits with Travis talking about how he's going to kill his wife for cheating on him with a black man. He's credited as "Man Watching Silhouette".
Visible crew/equipment: In the scene right after DeNiro is watching the Senator on the TV, he is driving in his cab past the campaign headquarters. As the camera goes past the window and focuses on desk phone, you can see the reflection of a cameraman for a second or so in the glass. (00:51:00)
Continuity mistake: Taking a fatal bullet from Travis, the robber falls back. He is not just breaking the snack display cabinet, but also knocking one of the dirty Spanish magazines off the clothesline. The magazine falls with him and gets all crimpled between his arm and the counter, but vanishes entirely in the rest of the scene. (01:08:50)
Revealing mistake: When the Senator finishes his speech and steps off the stage, Travis begins to move making his way through the crowd. Several extras are recycled appearing in inconsistent positions - look no further than the black woman with a bright flower patterned pink shirt; she is simultaneously in front of Travis as he begins to move in the outer section, and right between Charles Palantine and the stage in the shot immediately after. And then she keeps popping up where she's not supposed to be, continuously. (01:36:20)
Revealing mistake: When Travis starts spelling his phony name out to the security guy, a ginger kid walks in, stares at the camera, and hides away as quick as he came. In similar fashion, another kid with a red baseball cap looks at the camera behind De Niro once this walks by evading the photographer. (01:04:20)