Ferris could have easily - and plausibly - avoided detection at the parade by wearing a "carnival" mask. Of course, thanks to his being The Ace (see main page), he pulls it off anyway.
Obviously it's a comedy so it's something that wasn't worth addressing, but how the hell did Cameron get away with wearing a Detroit Red Wings jersey in the middle of Chicago? It's one of the most bitter rivalries in North American sports.
It signals how out-of-sync Cameron is with the world around him. He may even intentionally be wearing a team jersey that alienates him further at school and in the city.
Did Ferris actually think Cameron was going to be okay by the end of the movie? Cameron's father was probably already physically abusive (look at how utterly TERRIFIED Cameron was of the guy), and Cameron just wrecked not only the expensive garage, but also the thing that Mr. Frye loved more than anything else, possibly the only thing he loved at all. Cameron's lucky if he isn't beaten to death. - It was never implied to be physical abuse. Teenagers can be terrified of verbally abuse parents too. But really the movie only suggests that Cameron hates conflict and his father is an asshole.
Why does Cameron wear suspenders and a belt? To illustrate how uptight and insecure he is.
The art museum scene might at first glance just seem like a playful montage of teens goofing off in an art museum, but one element stands out; Cameron's fixation with the George Seurat's "A Sunday Afternoon on the Island of La Grande Jatte". The famous sequence features alternating shots of Cameron and the painting each one closer then the last until at last it zooms in on a single blotch of paint. One might dismiss this scene as just a portrayal of the fun of impressionist paintings, but considering the subject matter of "A Sunday Afternoon" it seems more likely to be a key moment for Cameron's character. The painting shows people arranged as though on a chessboard all facing right angles. The exception to this are children and animals who are shown frolicking freely and naturally in the scene. The intent of the painting was to criticize the rigid social constraints of Victorian society. The exact spot Cameron is staring at is the face of a little girl. Unlike the animals and the other child in the picture this girl is walking with her mother, holding her hand, seemingly pulled into the rigid pattern that all the other painted characters are trapped in. Considering Cameron's relationship with his parents this seems like a very relevant thing for him to be fixated on.
actually Word of God says that the painting was made with pointillism and how, the closer you look at it, the less you see, and Cameron became fixated with it because he was afraid that, just like the painting, the more you looked at him, the less you see, he was nothing.
There are some people out there who wonder why Ferris takes his friends to places like a museum and a French restaurant instead of places like an arcade or the mall. Ferris is Genre Savvy enough to know that going to those place would be too conspicuous for a teen who is ditching school. Even Rooney thought that Ferris might be at a pizza joint.