I really don’t know about the “mime act,” but sometimes the laity are permitted to give a “reflection,” in lieu of a homily.
No it is not permitted. Can. 767 §1. Among the forms of preaching, the homily, which is part of the liturgy itself
and is reserved to a priest or deacon, is preeminent; in the homily the mysteries of faith and the norms of Christian life are to be explained from the sacred text during the course of the liturgical year.
§2.
A homily must be given at all Masses on Sundays and holy days of obligation which are celebrated with a congregation, and it cannot be omitted except for a grave cause.
§3. It is strongly recommended that if there is a sufficient congregation, a homily is to be given even at Masses celebrated during the week, especially during the time of Advent and Lent or on the occasion of some feast day or a sorrowful event.
§4. It is for the pastor or rector of a church to take care that these prescripts are observed conscientiously.
Note in §1 the part about the homily being
reserved to the priest or deacon. That means that a layperson cannot give a homily. Note in §2 that a homily is REQUIRED on Sundays and Holy Days of Obligation.
Calling it a “reflection” instead of a “homily” doesn’t change anything. If it is a talk given after the reading of the Gospel and before the Profession of Faith, it is a homily.
Also, see the General Instruction of the Roman Missal:65. The homily is part of the Liturgy and is strongly recommended,[63] for it is necessary for the nurturing of the Christian life. It should be an exposition of some aspect of the readings from Sacred Scripture or of another text from the Ordinary or from the Proper of the Mass of the day and should take into account both the mystery being celebrated and the particular needs of the listeners.[64]
- The homily should ordinarily be given by the priest celebrant himself. He may entrust it to a concelebrating priest or occasionally, according to circumstances, to the deacon, but never to a lay person.[65] In particular cases and for a just cause, the homily may even be given by a Bishop or a priest who is present at the celebration but cannot concelebrate.
There is to be a homily on Sundays and holy days of obligation at all Masses that are celebrated with the participation of a congregation; it may not be omitted without a serious reason. It is recommended on other days, especially on the weekdays of Advent, Lent, and the Easter Season, as well as on other festive days and occasions when the people come to church in greater numbers.[66]
And Instruction Redemptionis Sacramentum:[64.] The homily, which is given in the course of the celebration of Holy Mass and is a part of the Liturgy itself,[142] “should ordinarily be given by the Priest celebrant himself. He may entrust it to a concelebrating Priest or occasionally, according to circumstances, to a Deacon, but never to a layperson.[143] In particular cases and for a just cause, the homily may even be given by a Bishop or a Priest who is present at the celebration but cannot concelebrate”.[144]
[65.]
It should be borne in mind that any previous norm that may have admitted non-ordained faithful to give the homily during the eucharistic celebration is to be considered abrogated by the norm of canon 767 §1.[145] This practice is reprobated, so that it cannot be permitted to attain the force of custom.
Having said the above, a layperson can be permitted to address the congregants briefly during the Mass, but this is
in addition to the homily and is to be done after the Communion Rite and before the dismissal. From RS:[74.] If the need arises for the gathered faithful to be given instruction or testimony by a layperson in a Church concerning the Christian life, it is altogether preferable that this be done outside Mass. Nevertheless, for serious reasons it is permissible that this type of instruction or testimony be given
after the Priest has proclaimed the Prayer after Communion.
This should not become a regular practice, however. Furthermore, these instructions and testimony should not be of such a nature that they could be confused with the homily,[156]
nor is it permissible to dispense with the homily on their account.
The point being that there is a time and place for everything (well, except mimes). The time and place for the laity to speak is NOT when the homily should be given.