In the intro cutscene talking about the story of the Lost City and how the Numerians captured Mathra, the city gate that closes has the doors slide. Later, after Joni and Santiago reach the gate to the Lost City after finding the two keys that magically merge into one after being removed from the former's backpack, the gate's doors swing open.
If the player repetitively clicks on Joni's backpack, the backpack that shows up on the screen is only shown closing and repeating the same animation. However, the later game "5th Grade Adventures" fixed this so the backpack displayed on the screen is shown to open and close and vice-versa if the player repetitively clicks on her backpack.
Leslie Clark's character profile in this game has her in the 6th grade and described as having skipped a grade, and was given the age of 11. In later games in this series that chronologically follow the events of this game, she is given the age of 10 while still in the 6th grade.
Even though the Chest Monkey when playing the activity game Treasure Chest is female in most regional releases of this game, the UK version depicts her being a male.