Angel crashes his toy plane on purpose. The two shots of the wreckage are completely different.
When Hutch parks and covers Kate's car in her driveway, it's a Mercedes Benz. However, when it blows up it's clearly a 1966 Ford Mustang that's disguised with the tarp and Mercedes' hub caps and trim.
When Kate arrives to James Brady's office to arrange her assassination, when the case is not known yet by Starsky and Hutch, the Torino is parked just in front.
Before Hutch goes out to meet Starsky outside Kate's house, the actors marks at Kate's door are clearly visible before Kate and Hutch move on to them.