It cannot be presented as a confirmed fact that a cup with pens in Joe Cabot's office announces the identity of the infiltrator in Reservoir Dogs. The claim combines a set design description and a narrative interpretation, and the precise arrangement of the objects has not been corroborated, nor has any explanation from the crew been verified to attribute that function to them. For that reason, it is not accurate to describe the colour, contents or position of the supposed cup as if they were established facts.
The film does indeed use colour-coded aliases for the participants in the heist. That fact may suggest associations to viewers, but it does not automatically turn any coloured object into a clue. Mr. Orange's identity has a narrative development that can be understood without resorting to this hypothesis about the set dressing.
Nor is it right to say that the clue is disproved because a screenplay does not describe the object. Written text and staging do not always contain the same details. The conclusion is more limited: this explanation of the cup does not have enough support to be treated as an established key to the film.
What is being attributed to the supposed cup
The claim suggests that a pen holder in Joe's office foreshadows a betrayal. To support it, one would first need to establish the visual detail and then the narrative relationship assigned to it. In this case, there is no corroborated image that allows the location and arrangement described to be accepted as correct. That framing cannot be reconstructed by adding colours or positions that have not been verified.
The association is conceivable because the colour names do serve an explicit function: Joe assigns them as aliases to limit personal information among the members of the group. That procedure belongs to the dialogue and to the identification of the characters. Extending it to the contents of his desk requires an additional link that the mere existence of the nicknames does not provide.
Quentin Tarantino's draft dated 22 October 1990, held by IMSDb, can be consulted to study the group's presentation. However, it does not allow this reading of the set dressing in the released film to be confirmed. The absence of a written indication also does not prove that an object did not appear during filming: that would be a different and broader conclusion than the available documentation allows.
The identity of the infiltrator has another narrative basis
The film establishes Mr. Orange's police role through actions and dialogue. The reveal of the infiltrator changes what the viewer knows and gives meaning to his earlier preparation. That information does not depend on recognising a container or interpreting a colour code in the office. The story retains its explanation even when the audience has not noticed any detail of that kind.
A distinction must also be made between what the audience discovers and what Joe knows at each moment. If an element of the set could be interpreted as a warning sign for the viewer, that would not prove that the character was aware of the infiltration. Attributing knowledge to Joe on the basis of an object in his space would add a plot conclusion that the visual hypothesis also does not establish.
The defensible formulation is therefore limited: a reading of cups and pens as a foreshadowing is proposed, but the detail described and any authorial intention have not been confirmed. There is no basis for attributing such an explanation to Tarantino, for considering it proof of the policeman's identity, or for turning it into a scene different from the one the film actually presents.
The word rat is used here to refer to the undercover police officer among the participants in the robbery. Describing him as a traitor adopts the gang's point of view, as they believe they are working with another criminal. They are two ways of naming the same position within the conflict, even if they do not express the same viewpoint. That difference matters when an interpretation of the set promises to announce a betrayal: it needs to make clear to whom the supposed announcement is directed and from what knowledge it is being interpreted.
The alias Mr. Orange identifies the character within the group; it is not a description of every object that may be associated with him. The coincidence of a colour word with a visual element, if one were located, would allow an association to be proposed. By itself, it would not explain when the viewer is meant to recognise it or what new information it provides. The question about the cups is limited to that specific attribution, without altering the identity established by the film through the development of its story.