After more than three millennia of Ancient Egyptian language continuity and change, language contact between Ancient Egyptian and Arabic resulted in a language shift from the Ancient Egyptian, in its Coptic stage, into Arabic. Despite the shift, Coptic continued to be used as a liturgical language by the Christians in Egypt. Moreover, traces of the Ancient Egyptian linguistic features influenced Egyptian Arabic, the Arabic variety used in Egypt since the shift. This contribution aims to outline several theoretical and practical challenges, which face a systematic study of the Ancient Egyptian interference through shift (substratum interference) into Egyptian Arabic. It also discusses the importance of studying Ancient Egyptian traces in Egyptian Arabic, as an additional source to the abandoned Ancient Egyptian language, for a better understanding of the Ancient Egyptian language and culture. Following an introduction and emphasis on the difference between Egyptian Arabic and standard Arabic, the paper discusses several examples of lexical survivals as well as Coptic substratum syntactic, and morphological features of Egyptian Arabic. Finally, the paper presents an example of substratum Ancient Egyptian cultural concepts, which is represented in contemporary Egyptian Arabic.