While there are dozens of squirrels to be found on House of Horrors, the real easter egg lies within the design of the track; it crosses paths with Condemned Complex.
There are 20 squirrels in this map, as well as an easter egg which is unrelated to the squirrels.
The first squirrel floats by a window after the first checkpoint.
Right after the second checkpoint, there will be a large squirrel shadow cast on the wall.
Shortly after the fourth checkpoint, there will be a water fountain with 3 squirrels sticking out, spewing water.
After the fifth checkpoint, look for the fireplace in the background. There will be 3 more squirrels stuck in the wall above the fireplace.
Right after the 7th checkpoint, you'll jump on book shelf, beyond that, there is a platform with a railing. You'll notice further than that, there is a doorway. Watch carefully as a squirrel floats past the opening.
At the finish line, there are 4 squirrels on spinning logs.
After crossing the finish line, an additional 7 squirrels fall down on top of the player after completing the map.
Additionally, right after the giant squirrel shadow, if you look carefully off into the background, you'll notice that this map intersects with Condemned Complex, a map packaged with the Big Pack map pack. The map intersects in the area where the first loop is in Condemned Complex.
As of yet, it is not known whether this crossing of tracks is significant in any way.
This section is reserved for Confirmation/comments about this investigation. Investigations will remain open until advised by Redlynx that the final solution for each secret is found.