[Chapter 67]

And now the angels are making a wooden (building), and when they have completed that task I will place My hand upon it and preserve it, and there shall come forth from it the seed of life, and a change shall set in so that the 3 earth will not remain without inhabitant.

Comment: This is an obvious reference to the ark. However it was not built by angels. The task of doing this was given to Noah.

Genesis 5:12-15
God saw how corrupt the earth had become, for all the people on earth had corrupted their ways. So God said to Noah, “I am going to put an end to all people, for the earth is filled with violence because of them. I am surely going to destroy both them and the earth. So make yourself an ark of cypress wood; make rooms in it and coat it with pitch inside and out. This is how you are to build it: The ark is to be three hundred cubits long, fifty cubits wide and thirty cubits high.

The errors the writers of the Book of Enoch adds up eventually, and it becomes evident that it is not an inspired book. Meaning it is not from God that this book has its origin. Subtle errors is errors nontheless. This is an exercise you can also do with other apocryphical books to see why they have not been included in the Bible. Most of them have more obvious errors than the Book of Enoch and you can certainly see why the early church did not recognize them as Scripture.