During the opening sequence in the park, the soap bubble containers have UPC bar codes upon them. The Universal Product Code technology existed in 1973, but was currently in product testing only in a Kroger store in Cincinatti, Ohio, and another in Troy, Ohio. The UPC was not printed upon the labels of commercial items for another three years, and then only on a select few items.
In the stakeout scene, the first man to pass Detective Chris Skelton is wearing a 'Members Only' jacket. The brand wasn't created until 1975 and not introduced to the American market until 1979. The specific jacket design was not introduced until 1981.
When Detective Tyler goes into what he believes is his childhood home, you can see a man holding open the door with a soda in his hand as Detective Tyler walks into the room with the loose floor board.