Rashi, together with other commentators claims that the Commandment to build the Mishkan was given after the sin of the Golden Calf ("Chet Ha'egel"), i.e. the sections are not in chronological order.
At first, this interpretation seems senseless. Why should the Torah record at this specific point the mitzvot which he did not receive at this time, while omitting all the mitzvot which He did receive at this time? What leads Rashi to this absurd conclusion?
Just as similarities exist between the Mishkan and "Ma'amad Har Sinai" (when Moses ascended Mount Sinai), so do very striking similarities exist between the construction of the Golden Calf and the Mishkan. One example is the manner in which gold was collected from the people, melted down and formed. Because of these similarities, Rashi concludes that God's commandment to build the Mishkan must have been given after, and because of, Chet Ha'egel.