In the kitchen in Louis' house there's a poster with Temple Grandin's name on it. Grandin is autistic, and an outspoken and influential person in neurodiversity advocacy.
Michiel Huisman and Michael McElhatton were both in Game of Thrones (2011), although they never shared any scenes together. Brian Cox, who was approached for that series but declined, did share the scene with McElhatton in The Autopsy of Jane Doe (2016).
Eleanor O'Brien and Niamh Algar also feature in The Wonder.
Like Daniel, Padraig's surname is Murphy.
Sullivan's funeral services calls Daniel at 10.43, Crowley calls at 13.00, Ger calls at 14.27.