I think it is the shadow right above the green mitten on the I-Spy year round challenger book.
The button pin on page 14 that says βExpertβ is the fourth button in ispy year round challenger.
In a photo to the left of the people playing the piano and the rollerskate
It is in the top left- hand window on page 26
On pages 14 and 15 of the Spy Year Round Challenger book, the four buttons are located on the bottom right corner. Look for the buttons labeled with icons or arrows to navigate through the pages or access additional features.
Under the white bear in the bottom left side of the high left window.
It is on the fourth dog from the left. It is on the dogs nose.
That's a tricky one. The first two bows are on the red present and the red bow on the holly. Since this is a challenger book you have to think out of the box. The other two are held by the bears playing the violin! :) They are violin bows! Tricky tricky!
The queen is sticking out in the lower left hand side of the valentine mailbox on page 10 and is a playing card
The elfin nose is right next to the cows tongue and directly below the alien mask that is to the left of the milky way
I think it's on the penny and the ruler. VERY hard to see... We actually took a picture and then zoomed in to see them.
I was looking for that tonight. No earthly idea. Maybe the editors thought the snowman's scarf was blue (looks green)