The bird Jessamy is thought by some viewers to be a magpie due to her coloration; if true, this would make it a goof that the characters all refer to her as a raven. However, her body shape is not that of a magpie. She is actually an African raven of the species Corvus albus, also called the "pied crow", which gets its name from its distinctive white markings.
Right after the title year 1926 appears (30:26), the son of Roderick Burgess is reading a book on the lawn. The book is A Handful of Dust by Evelyn Waugh. This book was published in 1934. The error is the title year and it should be 1936 instead.
It says it's the year 1926. The book Vile Bodies is mentioned. However, that book wasn't published until 1930.
Benedick Blythe is credited as playing Alex Burgess (70), and Benjamin Evan Ainsworth is credited as playing Alex Burgess (6). This means that between the first time Alex is seen, before Dream's imprisonment and the last time Alex is seen, when Dream escapes, 64 years have passed. However Dream tells Alex he has been imprisoned for a century.