Found the following hamletworks.org entries referring to line 54

View Commentary Note for 38
38 He may approoue our eyes and speake to it. 1.1.29

View Commentary Note for 51-52
51 {Enter Ghost.}1.1.40
51-52 Mar. Peace, breake thee of, <Enter the Ghost.> | looke where it comes againe.

View Commentary Note for 54
54 Mar. Thou art a scholler, speake to it Horatio.1.1.42

View Immaterial Textual Note for 54
54 Mar. Thou art a scholler, speake to it Horatio.1.1.42

View Material Textual Note for 54
54 Mar. Thou art a scholler, speake to it Horatio.1.1.42

View Commentary Note for 55
55 Bar. Lookes {a} <it> not like the King? marke it Horatio.1.1.43

View Commentary Note for 58
58 Mar. {Speake to} <Question> it Horatio.1.1.45