[1] Leopold Zunz ascribes the composition of the entire work to the 11th or 12th century; although, immediately following Bereshit Rabbah in the collection of the rabbot, it "is separated from the latter by 500 years".
[2] It was first quoted by Azriel of Gerona and then by Nachmanides, placing its composition no later than the early 13th century.
[3] In sections 1-14 the proems are almost invariably followed by the running commentary on the entire seder or other Scriptural division (the beginnings of the sedarim are distinguished by an asterisk): There is no exposition, nor (in the Tanhuma midrashim) any homily, to *Exodus 11:1.
In the printed editions the text is sometimes abbreviated and the reader referred to such collections, as well as to the Pesikta Rabbati; in section 39 the entire exposition of the Pesikta Rabbati lesson Ki Tissa (Exodus 30:11) has been eliminated in this fashion.
There is an interesting statement in section 44 regarding the manner of treating a proem-text from the Psalms for the homily to Exodus 32:13.