At the end when Abby got the calendar back, and day 25's door opens, she starts to have flashbacks of what happened with each gift on each day. The very first flashback she has is Josh saying "I came back for you". That hadn't happened in the movie yet though, she meets Josh later that night and he says it then. So she couldn't have flashed back on that.
Although the film is set in the US (possibly NJ as shown on a poster in a cafe), the Canadian ice cream company COWS shows up in the background several times. (The movie was filmed in Niagara-on-the-Lake, Ontario, Canada).
When they guys are waiting for Abby to show up in front of the theater, Fernando gets mad at Josh for using a cellphone and says "Nobody uses cellphones in A Christmas Story, it's 1983!" The story line of A Christmas Story is actually the 1940s, the movie was simply released in 1983.
At around the 1 hour mark, in the scene where Abby is standing next to the new Santa photographer after the auction, you can see the Canon cover is still on the lens even though she's supposedly taking pictures.